Ch 1Measurement
5-Mark Questions
Name some common systems of measurement.
There are several common systems of measurement used to express physical quantities. The FPS system uses Foot for length, Pound for mass, and Second for time. The CGS system uses Centimetre for length, Gram for mass, and Second for time. The MKS system uses Metre for length, Kilogram for mass, and Second for time. Among these, the MKS system forms the basis of the International System of Units (SI), which is the most widely used system in science and engineering today. Each system has its own advantages and is used in different contexts depending on the region and field of application. …
What are the differences between Plane angle and solid angle?
Plane angle and solid angle are two different types of angles used in geometry and physics. A plane angle is formed by the intersection of two lines or two planes and is two-dimensional in nature. The unit of plane angle is the radian. A solid angle, on the other hand, is formed by the intersection of three or more planes at a common point and is three-dimensional in nature. The unit of solid angle is the steradian. Plane angles are commonly used in two-dimensional geometry and trigonometry, while solid angles are used in three-dimensional geometry, optics, and radiation studies. …
2-Mark Questions
How many base quantities are included in SI system?
Seven.
Give the name of the instrument used for the measurement of temperature.
The instrument used for the measurement of temperature is a thermometer. A thermometer is a device that contains a liquid (such as mercury or alcohol) or uses electronic sensors to measure the degree of hotness or coldness of a substance or environment. Thermometers work on the principle that liquids or materials expand or contract with changes in temperature, allowing us to read the temperature value on a calibrated scale.
What is the ‘Lower Fixed Point’ of the Fahrenheit scale?
The lower fixed point of the Fahrenheit scale is 32°F. This is the temperature at which water freezes under standard atmospheric pressure. The Fahrenheit scale was established with two fixed points: the lower fixed point at 32°F (freezing point of water) and the upper fixed point at 212°F (boiling point of water), with 180 equal divisions between them.
1-Mark Questions (MCQ)
Which one the following system of units is the British System of unit?
(c) FPS
Ch 2Forces and Pressure
5-Mark Questions
A stone weighs 500 N. Calculate the pressure exerted by it if it makes a contact with a surface of area 25 cm2.
Given : Weight of a stone F = 500 No Area A = 25 cm 2 = 25 x 10 -4 m 2 To find : Pressure P = ? Formula :Pressure P = 20 x 10 4 N/m 2 (or) 20 x 10 4 Pa
Give two examples to verify that a force tends to change the static condition of a body.
Force can change the static condition of a body. A rest rubber ball begins to move, when a force applied on it. Player applies a force on the stationary football while taking a penalty kick is football match. The force applied by player makes the football move towards the goal.
2-Mark Questions
Rolling friction, static friction, sliding friction
In order of increasing magnitude, the correct arrangement is: Static friction, Rolling friction, Sliding friction. Static friction is the maximum frictional force and acts when an object is at rest and tends to prevent it from moving. Rolling friction is smaller than static friction and acts on rolling objects. Sliding friction is the smallest of the three and acts when an object slides over a surface. This ordering reflects the relative magnitudes of frictional forces in different types of motion.
Give two examples to verify that a force changes the shape of a body.
Force can change the static condition of a body. If you squeeze a sponge, its shape changes. If you pull a rubber band, it becomes longer.
What do you feel when you touch a nail immediately after it is hammered into a wooden plank? Why?
When you touch a nail immediately after it is hammered into a wooden plank, you feel that it is hot. This happens because friction between the nail and the wood generates heat. As the hammer strikes the nail repeatedly, the kinetic energy of the moving nail is converted into heat energy due to the friction between the nail and the wooden plank. The friction force opposes the motion of the nail, and the work done against this friction is transformed into thermal energy, raising the temperature of the nail significantly.
1-Mark Questions (MCQ)
If we apply a force against the direction of motion of a body, then the body will –
(a) stop moving
Ch 3Light
5-Mark Questions
The radius of curvature of a spherical mirror is 25 cm. Find its focal length.
Given : Radius of curvature = 25 cm To find: f = ? f = \(\frac { R }{ 2}\) = \(\frac { 25 }{ 2 }\) f = 12.5 cm
Give two applications of a concave and convex mirror.
Concave mirrors have several important applications due to their ability to converge light and produce magnified images. One major application is in personal grooming, where concave mirrors are used while applying make-up or shaving because they provide a magnified, upright image of the face, allowing for precise application and better visibility of details. Another important application is in lighting devices such as torches, search lights, and vehicle headlights. …
2-Mark Questions
What is called a spherical mirror?
A spherical mirror is a curved mirror that forms a part of a sphere. It is created when a reflecting surface is curved in the shape of a portion of a sphere. Spherical mirrors are one of the two main types of curved mirrors used in optics. They are called spherical because their reflecting surface is a segment of a spherical surface. Spherical mirrors can be further classified into two types: concave mirrors, which curve inward and converge light rays, and convex mirrors, which curve outward and diverge light rays.
Define focal length.
The focal length of a spherical mirror is defined as the distance between the pole of the mirror and its principal focus. The pole is the geometric centre of the mirror's reflecting surface, and the principal focus is the point where parallel rays of light converge after reflection from a concave mirror, or appear to diverge from after reflection from a convex mirror. Focal length is denoted by the symbol 'f' and is an important parameter that determines the optical properties of the mirror. …
Explain the images formed by a concave mirror?
A concave mirror forms different images depending on object position: an object beyond the centre of curvature (C) gives a real, inverted, diminished image between C and the focus (F); an object at C gives a real, inverted image of the same size at C; an object between C and F gives a real, inverted, magnified image beyond C; an object at F produces an image at infinity; an object between F and the pole gives a virtual, erect, magnified image behind the mirror.
1-Mark Questions (MCQ)
Mirrors having a curved reflecting surface are called as –
(b) Spherical mirrors
Ch 4Matter
5-Mark Questions
What does a chemical symbol represent?
A chemical symbol is a shorthand method of representing an element using one or two letters, where the first letter is always a capital letter and the second letter, if present, is a lowercase letter. A chemical symbol represents two important pieces of information about an element. First, it represents the name of the element itself. For example, the symbol O stands for the element oxygen, the symbol H stands for hydrogen, and the symbol C stands for carbon. Second, a chemical symbol represents one atom of that element. …
Write three properties of metalloids.
Metalloids possess several distinctive properties that set them apart from both metals and non-metals. First, metalloids are all solid at room temperature, maintaining a solid state under normal conditions. Second, metalloids can form alloys with other metals, combining with metallic elements to create useful materials with enhanced properties. Third, some metalloids such as silicon and germanium can act as electrical conductors under specific conditions, and for this reason they are called semiconductors. …
2-Mark Questions
The Pictorial symbol for water given by the alchemists was –
Write the constituent elements and their symbols for the following compounds Carbon monoxide Washing soda
Compound Symbols Constituent elements Carbon monoxide (CO) Carbon and oxygen Washing soda (Na 2 CO 3 ) Sodium, carbon and oxygen
Write the symbols for these elements Oxygen Gold Calcium Cadmium Iron
S.No Element Symbols (i) Oxygen O (ii) Gold Au (iii) Calcium Ca (iv) Cadmium Cd (v) Iron Fe
1-Mark Questions (MCQ)
The liquid metal used in thermometers is –
(b) Mercury
Ch 5Changes Around Us
5-Mark Questions
Define a chemical reaction. .
A chemical reaction is a process in which one or more substances, called reactants, undergo a transformation to form one or more new substances, called products. During a chemical reaction, the chemical bonds within the reactant molecules are broken, and new chemical bonds are formed to create the product molecules. This process can be represented by the equation: Reactant(s) → Product(s). …
What happens when an iron nail is placed in copper sulphate solution?
When an iron nail is placed in a copper sulphate solution, a displacement reaction occurs. Iron is more reactive than copper and displaces copper from the copper sulphate solution. As a result, ferrous sulphate is formed and copper metal is deposited on the surface of the iron nail. The blue colour of the copper sulphate solution gradually changes to green due to the formation of ferrous sulphate, which is green in colour. The iron nail becomes coated with a reddish layer of copper metal as the reaction progresses. …
2-Mark Questions
Mention the various conditions required for a chemical reaction to occur.
Various conditions are required for a chemical reaction to occur. These include physical contact between reactants, which allows them to interact. The reactants may need to be in solution form to facilitate the reaction. External energy sources such as heat, light, or electricity can initiate or accelerate chemical reactions. Additionally, a catalyst, which is a substance that speeds up the reaction without being consumed, may be required. Some reactions occur spontaneously at room temperature, while others require specific conditions like high temperature or pressure to proceed. …
Define catalysis.
Catalysis is the process by which the speed of a chemical reaction is altered by a substance called a catalyst. A catalyst is a chemical substance that increases or decreases the rate of a reaction without itself being permanently changed or consumed in the reaction. Catalysts work by providing an alternative pathway for the reaction with lower activation energy, allowing reactants to convert to products more quickly. The catalyst remains chemically unchanged at the end of the reaction and can be used repeatedly. Catalysts are essential in many industrial processes and biological systems. …
On heating, calcium carbonate gives calcium oxide and oxygen. Is it exothermic reaction or endothermic reaction?
The decomposition of calcium carbonate on heating to produce calcium oxide and oxygen is an endothermic reaction. This is because heat energy must be continuously supplied to break the chemical bonds in calcium carbonate and convert it into calcium oxide and oxygen gas. The reaction requires external energy input to proceed, which is the defining characteristic of an endothermic reaction. Without continuous heating, the reaction will not occur or will stop. …
1-Mark Questions (MCQ)
Burning of paper is a …………….. change.
(b) Chemical
Ch 6Micro Organisms
5-Mark Questions
Write the four types of bacteria, based on their shape.
Bacteria are described according to the shape of their cells. They are: Bacilli – Rod shaped bacteria. Spirilla – Spiral shaped bacteria. Cocci – Spherical or ball shaped bacteria. Vibrio – Comma shaped bacteria.
How diseases causing micro organisms enter into human beings?
Disease-causing microorganisms are called pathogens, and they enter the human body through several different routes. Pathogens can enter through cuts and wounds in the skin, mouth, or nose, directly accessing the bloodstream or internal tissues. Some pathogens are airborne and enter a healthy person by breathing contaminated air. When a patient sneezes or coughs, droplets containing microbes spread into the air and can be inhaled by others, as seen in diseases like tuberculosis and influenza. …
2-Mark Questions
Write the name of any nitrogen fixing bacteria.
Rhizobium.
Name the bacteria used in the production of vinegar.
Acetobacter aceti.
Write the names of any three protozoans.
Amoeba Plasmodium Paramecium.
1-Mark Questions (MCQ)
Micro organisms are measured in ……………..
(c) micron
Ch 7Plant Kingdom
5-Mark Questions
What is mean by Binomial Nomenclature? Give example.
Binomial Nomenclature is a system of naming organisms using two Latin words, which was developed by Carl Linnaeus. The first word represents the genus name and is written with a capital letter, while the second word represents the species name and is written in lowercase. Both words are italicized or underlined. For example, the binomial name of mango is Mangifera indica, where Mangifera is the genus and indica is the species. Similarly, the binomial name of humans is Homo sapiens. …
Write any two points of dicotyledons.
Seed has two cotyledons. Plants have tap root system, leaves with reticulate venation. Flowers are tetramerous or pentamerous. Calyx and corolla are well differentiated. Pollination occurs mostly by insects.
2-Mark Questions
Define Thallus.
Thallus refers to a plant body that is not differentiated into roots, stem, and leaves. It is a simple, undifferentiated body structure found in lower plants such as algae, fungi, and liverworts. The thallus performs all life functions without specialized organs, and the entire structure is involved in photosynthesis and absorption of nutrients.
Seeds of gymnosperm plants are naked. Why?
Seeds of gymnosperm plants are naked because in gymnosperms, the ovules are borne directly on the surface of megasporophylls or cone scales, and no flowers are produced. Since the ovules are not enclosed within an ovary or fruit, the seeds remain exposed or naked after fertilization. This is why gymnosperms are also called open seed-bearing plants, in contrast to angiosperms where seeds are enclosed within a fruit.
How many classes are there in Bryophytes? What are they?
Bryophytes are classified into 3 classes. Class I: Hepaticae (Liverworts) Example: Riccia. Class II: Anthocerotae (Homworts) Example : Anthoceros Class III : Musci (Mosses) Example: Funaria
1-Mark Questions (MCQ)
Solanum trilobatum is the binomial name of Thoothuvalai. Here the word ‘Solanum’ refers to …………….
(b) Genus
Ch 8Organisation of Life
5-Mark Questions
What is cell differentiation?
Cell differentiation is the process by which cells become specialized in structure and function during development. Our body develops from a single cell called the zygote, which undergoes mitotic division to produce many cells. As development progresses, these cells undergo changes in their structure, size, and content, acquiring specific characteristics that enable them to perform specialized functions. This process of acquiring specialized structures and functions is called differentiation. …
State different types of tissues.
Tissues are groups of similar cells that work together to perform a specific function. Based on their structure and function, tissues can be classified into four main types. Epithelial or covering tissue forms protective layers on the body surface and lines internal organs, providing protection and controlling the exchange of materials. Muscular or contractile tissue is responsible for movements and locomotion by contracting and relaxing. Connective tissue provides support and binds different structures of the body together, including bone, cartilage, and blood. …
2-Mark Questions
Tissues, organ system, organism, cell, organ
The correct hierarchical order of organization from smallest to largest is: Cell, tissues, organ, organ system, organism. A cell is the basic unit of life, tissues are groups of similar cells performing a specific function, organs are structures made of different tissues working together, organ systems are groups of organs functioning together, and an organism is a complete living individual composed of multiple organ systems.
Name the processes by which air enters and comes out of our lungs?
The process of taking air into the lungs is called inspiration or inhalation. During this process, the diaphragm contracts and moves downward, the rib cage expands, and the volume of the thoracic cavity increases, allowing air to flow into the lungs through the nose and mouth. The process of expelling air from the lungs is called expiration or exhalation. During this process, the diaphragm relaxes and moves upward, the rib cage contracts, and the volume of the thoracic cavity decreases, pushing air out of the lungs through the nose and mouth. …
Define Prokaryotic cell?
Prokaryotic cells are cells that lack a true nucleus and other membrane-bound organelles. In prokaryotic organisms, the genetic material (DNA) is not enclosed within a nuclear membrane but instead exists freely in a region called the nucleoid. Prokaryotic cells are typically smaller and simpler in structure compared to eukaryotic cells. Examples of prokaryotic organisms include bacteria and archaea. …
1-Mark Questions (MCQ)
……………… is tough and thick white sheath that protect the inner parts of the eye.
(a) Sclera
Ch 9Heat
5-Mark Questions
What are the applications of conduction in our daily life?
Conduction has numerous practical applications in our daily life. We cook food in vessels made up of metals such as aluminum or steel because metals are excellent conductors of heat. When the vessel is heated on a stove, heat is efficiently transferred from the metal to the food inside through conduction. When we iron clothes, heat is transferred from the hot iron plate to the fabric through conduction, allowing us to remove wrinkles. …
Write a note on convection.
Convection is the form of heat transfer from places of high temperature to places of low temperature by the actual movement of molecules. In this process, the molecules themselves move from one location to another, carrying thermal energy with them. Convection takes place in liquids and gases because the molecules in these fluids are free to move about, unlike in solids where molecules are fixed in their positions. When a liquid or gas is heated, the molecules at the heated region gain energy and move faster, becoming less dense and rising upward. …
2-Mark Questions
What are the effects of heat?
Heat produces three main effects on substances. The first effect is expansion, where the dimensions or volume of a substance increase when heat is applied to it. The second effect is an increase in temperature, which occurs when heat energy is absorbed by a substance and the average kinetic energy of its molecules increases. The third effect is a change in state, where a substance may transform from one physical state to another, such as from solid to liquid (melting), from liquid to gas (evaporation or boiling), or from solid directly to gas (sublimation).
Name three types of heat transfer.
The three types of heat transfer are conduction, convection, and radiation. Conduction is the transfer of heat through direct contact between materials, primarily occurring in solids where heat flows from regions of higher temperature to lower temperature through the vibration and collision of molecules. Convection is the transfer of heat through the actual movement of molecules in liquids and gases, where warmer, less dense portions rise and cooler, denser portions sink, creating circular currents. …
Define one calorie.
One calorie is the amount of heat energy required to raise the temperature of one gram of water through one degree Celsius. The calorie is a unit of heat energy commonly used in physics and chemistry. It is important to note that the calorie used in everyday contexts, such as in nutrition and food energy content, is actually the kilocalorie (kcal), which equals one thousand calories. One calorie is equivalent to approximately 4.18 joules in the International System of Units (SI). …
1-Mark Questions (MCQ)
Heat is a form of ………….
(c) thermal energy
Ch 10Electricity
5-Mark Questions
Two similar charges – acquires a positive charge Two dissimilar charges – prevents a circuit from overheating When glass rod is rubbed with silk – repel each other When ebonite rod is rubbed with fur – attract each other Fuse – acquires a negative charge
Two similar charges repel each other. When two objects carry the same type of charge, whether both positive or both negative, they experience a repulsive force that pushes them apart. Two dissimilar charges attract each other. When one object carries a positive charge and another carries a negative charge, they experience an attractive force that pulls them together. When a glass rod is rubbed with silk, the glass rod acquires a positive charge. …
When a glass rod is rubbed with silk cloth, both get charged.
When a glass rod is rubbed with a silk cloth, both materials become charged due to the transfer of electrons between them. The reason for this charge transfer lies in the difference in how tightly electrons are bound in each material. In a glass rod, the free electrons are less tightly bound compared to those in silk cloth. During rubbing, these loosely bound electrons from the glass rod are transferred to the silk cloth through friction. Since the glass rod loses electrons, it develops a deficiency of electrons and acquires a positive charge. …
2-Mark Questions
In an electroscope the connecting rod and the leaves are all metals.
In an electroscope, the connecting rod and the leaves are made of metals because metals are excellent conductors of electricity. Metals contain a large number of free electrons that can move easily through the material. This property allows the charge to travel freely from the metal disc through the connecting rod to the leaves without any obstruction. If non-conducting materials were used instead, the charge would not be able to move through the device, and the electroscope would not function properly. …
What is an electric circuit?
The path through which electrons flow from one terminal to the other terminal of a source is called an electric circuit.
1-Mark Questions (MCQ)
When an ebonite rod is rubbed with fur, the charge acquired by the fur is –
(b) positive
Ch 11Air
5-Mark Questions
Mention the physical properties of oxygen.
Oxygen possesses several important physical properties that define its behavior and applications. Oxygen is a colorless, odorless, and tasteless gas, making it imperceptible to human senses. It is a poor conductor of both heat and electricity, which limits its use in electrical applications. Oxygen dissolves readily in cold water, a property that is crucial for aquatic life as fish and other organisms depend on dissolved oxygen for respiration. It is denser than air, meaning it will sink below air in the atmosphere. …
List out the uses of nitrogen.
Nitrogen has numerous important industrial and practical applications. Liquid nitrogen is used as a refrigerant due to its extremely low temperature, making it valuable in preserving biological samples, food products, and other temperature-sensitive materials. Nitrogen provides an inert atmosphere for conducting certain chemical reactions, preventing unwanted oxidation or contamination during chemical processes. …
2-Mark Questions
Nitrogen – Respiration in living animals Oxygen – Fertilizer Carbon dioxide – Refrigerator Dry ice – Fire extinguisher
Nitrogen is used as a fertilizer because it is an essential nutrient for plant growth and is a major component of proteins and nucleic acids in living organisms. Oxygen is required for respiration in living animals, as it is used in the process of cellular respiration to release energy from food molecules. Carbon dioxide is used as a fire extinguisher because it does not support combustion and can displace oxygen around a fire, thereby extinguishing the flames. …
It is said that sleeping beneath the tree during night is bad for health. What is the reason?
During the night, trees undergo respiration, a metabolic process in which they consume oxygen and release carbon dioxide as a byproduct. Unlike photosynthesis, which occurs during the day and produces oxygen, respiration occurs continuously throughout the day and night. Therefore, during nighttime, trees absorb oxygen from the surrounding air and release carbon dioxide. Anyone who sleeps under a tree at night will be in an environment with reduced oxygen concentration and increased carbon dioxide concentration. …
1-Mark Questions (MCQ)
Which of the following is true about oxygen?
(d) Supports burning
Ch 12Atomic Structure
5-Mark Questions
Law of Conservation of Mass – Sir William Crookes Law of Constant Proportion – James Chadwick Cathode rays – Joseph Proust Anode rays – Lavoisier Neutrons – Goldstein
Law of Conservation of Mass – Lavoisier Law of Constant Proportion – Joseph Proust Cathode rays – Sir William Crookes Anode rays – Goldstein Neutrons – James Chadwick
Write the properties of anode rays.
Anode rays possess several important properties that distinguish them from cathode rays. Anode rays travel in straight lines in the absence of any external field. They are composed of material particles that carry mass and energy. Anode rays are deflected by both electric and magnetic fields, demonstrating their interaction with these fields. Since they are deflected towards the negatively charged plate in an electric field, they consist of positively charged particles. These positively charged particles are actually ions or atoms that have lost electrons. …
2-Mark Questions
State the Law of Conservation of Mass.
The Law of Conservation of Mass states that during any chemical change, the total mass of the products is equal to the total mass of the reactants. This fundamental principle means that matter cannot be created or destroyed in a chemical reaction, only rearranged. For example, when hydrogen burns in oxygen to form water, the mass of water produced equals the combined mass of hydrogen and oxygen that reacted. This law was established by Antoine Lavoisier and forms the basis for balancing chemical equations and understanding the nature of chemical reactions.
State the Law of Constant Proportions.
The Law of Constant Proportions states that in a pure chemical compound, the elements are always present in definite proportions by mass, regardless of the source or method of preparation. This means that any sample of a particular compound will always contain the same elements combined in the same mass ratio. For instance, water always contains hydrogen and oxygen in the ratio of 1:8 by mass, whether it is obtained from a well, river, or laboratory synthesis. This law demonstrates that compounds have a fixed composition and helps distinguish pure substances from mixtures.
Define valency of an element with respect to hydrogen.
The valency of an element with respect to hydrogen is defined as the number of hydrogen atoms that combine with one atom of that element. For example, in methane (CH₄), carbon has a valency of 4 because four hydrogen atoms combine with one carbon atom. In ammonia (NH₃), nitrogen has a valency of 3 because three hydrogen atoms combine with one nitrogen atom. Valency is a measure of the combining capacity of an element and helps in writing chemical formulas and understanding how atoms bond with each other.
1-Mark Questions (MCQ)
The same proportion of carbon and oxygen in the carbon dioxide obtained from different sources proves the law of
(b) definite proportion
Ch 13Movements
5-Mark Questions
Differentiate axial and appendicular skeleton.
The axial skeleton and appendicular skeleton are two main divisions of the skeletal system with distinct structures and functions. The axial skeleton consists of the bones along the central axis of the human body and includes the skull, facial bones, sternum, ribs, and vertebral column. These bones form the core framework of the body and protect vital organs such as the brain, heart, and lungs. The appendicular skeleton, on the other hand, contains the bones of the appendages and the structures that attach them to the axial skeleton. …
Differentiate tendons and ligament.
Tendon: They are made of elastic tissue. They attach muscle to a bone Ligament: They are short bands of tough fibrous connective tissues. They connect one bone to another
2-Mark Questions
Why our backbone is slightly movable?
Our backbone is slightly movable because the vertebrae are connected by gliding joints, which are slightly movable joints. These joints allow limited movement between adjacent vertebrae. The presence of intervertebral discs between the vertebrae also contributes to flexibility. This arrangement permits the backbone to bend forward, backward, and sideways, providing the body with the flexibility needed for various movements and postures while still maintaining structural support.
Define Muscle.
A muscle is a bundle of contractile tissue composed of muscle fibers that have the ability to contract and relax. Muscles have two main ends: the origin, which is the fixed end attached to a bone that does not move during contraction, and the insertion, which is the movable end that pulls another part of the body. When muscles contract, they shorten and pull on the bones to which they are attached through tendons, causing movement of body parts and enabling locomotion and various other functions.
1-Mark Questions (MCQ)
Which of the following parts of our body help us in movement? (i) Bones (ii) Skin (iii) Muscles (iv) Organs Choose the correct answer from the options below.
(a) (i) and (iii)
Ch 14Reaching the Age of Adolescence
5-Mark Questions
Puberty – Testosterone Adam’s apple – Muscle development Androgen – at 45 to 50 years of age ICSH – Sexual maturity Menopause – Change in voice
The correct matching of terms with their definitions is as follows: Puberty refers to the period of sexual maturity when reproductive organs become functional. Testosterone is the male hormone responsible for the development of male secondary sex characteristics. Adam's apple is the change in voice that occurs in boys during puberty due to the enlargement of the larynx. Androgen is the group of male hormones that promote muscle development and other male characteristics. ICSH, or Interstitial Cell Stimulating Hormone, stimulates the production of testosterone in males. …
List out the changes which occur during puberty.
Puberty is the period during which the body of a child transforms into that of an adult. This transformation involves several significant changes that occur over a period of time. The changes that occur during puberty include changes in body size, where there is a rapid increase in height and weight due to the growth spurt. Changes in body proportion occur as different parts of the body grow at different rates, altering the overall shape and structure. …
2-Mark Questions
What is secondary sex characteristics?
Secondary sex characteristics are the physical features and traits that develop during puberty and help distinguish males from females, but are not directly involved in reproduction. These characteristics include the growth of body hair in specific patterns, such as facial hair and body hair in males and underarm and pubic hair in both sexes. In females, secondary sex characteristics include the development of breasts and the widening of the hip region. …
1-Mark Questions (MCQ)
Adolescence is the period of life between ……………… years of age.
(c) 11 to 19
Ch 15Sound
5-Mark Questions
Ultrasonics – Frequency below 20Hz Speed of sound in air – Needs material medium Infrasonics – 330 m Sound propagation – Frequency more than 20000 Hz
Ultrasonics – Frequency more than 20000 Hz Speed of sound in air – 330 m Infrasonics – Frequency below 20Hz Sound propagation – Needs material medium
Give an example to show that light travels faster than sound.
Lightning: The most common example of showing that light travels faster than sound is lightning. Whenever a lightning strikes, you see the lightning first and then hear the thunder after some time.
2-Mark Questions
What is an ultrasonic sound?
A sound with a frequency greater than 20000 Hz is called as ultrasonic sound.
Mention few measures to be taken to reduce the effect of noise pollution.
Several important measures should be taken to reduce the effect of noise pollution. Strict guidelines and regulations should be set and enforced for the use of loudspeakers during social, religious, and political occasions to limit their duration and volume. All automobiles should be equipped with effective silencers to reduce the noise produced by engines and exhaust systems. Additionally, planting trees and creating green spaces helps absorb sound and reduces noise levels in urban areas. Noise barriers and sound-absorbing walls can be constructed along highways and near residential areas. …
A sound wave travels 2000 m in 8 s. What is the velocity of the sound?
Given data: Distance travelled by a sound wave d = 2000 m time taken t = 8s To find: Velocity of sound V = ? Formula:
1-Mark Questions (MCQ)
Sound waves travel very fast in …………..
(b) metals
Ch 16Magnetism
5-Mark Questions
Magnetite – Magnetic lines Natural A tiny pivoted magnet – magnet Cobalt – Compass box Closed curves – Ferromagnetic material Bismuth – Diamagnetic material
Magnetite – Natural magnet A tiny pivoted magnet – Compass box Cobalt – Ferromagnetic material Closed curves – Magnetic lines Bismuth – Diamagnetic material
What is artificial magnet? Give examples.
Artificial magnets are magnets that are made by people in a laboratory or a factory through various methods such as stroking, electrical induction, or electromagnetic means. These magnets are created to have specific properties and strengths according to their intended use. Examples of artificial magnets include horseshoe magnets, bar magnets, U-shaped magnets, cylindrical magnets, disc magnets, ring magnets, and electromagnets. Horseshoe magnets are shaped like a horseshoe and are commonly used in laboratories and industries. …
2-Mark Questions
What is magnetic field?
The space around a magnet in which its magnetic effect or influence is observed.
How can you identify non-magnetic materials? Give an example of a non- magnetic material.
Non-magnetic materials are materials that are not attracted by magnets and do not respond to magnetic force. To identify non-magnetic materials, you can bring a magnet close to the material and observe whether it is attracted to the magnet or not. If the material is not attracted to the magnet, it is a non-magnetic material. Examples of non-magnetic materials include wood, glass, rubber, plastic, and aluminium. These materials do not contain ferromagnetic properties and therefore do not experience any force of attraction when placed near a magnet.
1-Mark Questions (MCQ)
A magnet attracts ………………
(d) iron and steel
Ch 17Universe and Space Science
5-Mark Questions
Chandrayaan – Fuel Mangalyaan – Moon Cryogenic – First manned mission to the moon Apple – 8 – First man landing mission to the moon Apollo-11 – Mars
Chandrayaan – Moon Mangalyaan – Mars Cryogenic – Fuel Apple – 8 – First manned mission to the moon Apollo-11 – First man landing mission to the moon
What are the objectives of Chandrayaan-1?
The objectives of Chandrayaan-1 were to find the possibility of water on the Moon by detecting water molecules and ice deposits. Another objective was to find and map the elements and minerals present on the Moon's surface. The mission also aimed to search for the existence of Helium-3, which could be valuable as a future fuel source. Chandrayaan-1 was designed to make a detailed three-dimensional atlas of the Moon's topography and surface features. …
2-Mark Questions
The propellant of a rocket is only in the form of solids.
False Correct statement: The propellant of a rocket is may be in the form of solids or liquids.
What are celestial objects?
The stars, the planets, the Moon and any other objects like asteroids and comets in the sky are called celestial objects.
Define galaxy.
A collection of billions of stars held together by mutual attraction is called galaxy.
1-Mark Questions (MCQ)
Which of the following is a celestial body?
(d) All the above
Ch 18Water
5-Mark Questions
Name the gas evolved at cathode and anode when water is electrolysis. State their ratio by volume.
The gas which is evolved at cathode: Hydrogen (H 2 ). The gas which is evolved at anode: Oxygen (O 2 ) The ratio of H 2 and O 2 = 2 : 1.
State the importance of dissolved oxygen and carbon dioxide in water.
Dissolved oxygen in water is crucial for the survival of aquatic life. Fish extract dissolved oxygen from water through their gills and use it for respiration. Without sufficient dissolved oxygen, fish and other aquatic organisms cannot survive in water. Dissolved carbon dioxide in water is equally important as it is utilized by aquatic plants during photosynthesis to produce food and oxygen. Additionally, carbon dioxide dissolved in water reacts with limestone and other carbonate rocks to form calcium bicarbonate, which is soluble in water. …
2-Mark Questions
Water unfit for drinking is called potable water.
False Correct statement: Water suitable for drinking is called potable water.
Soap lathers well in hard water.
False Correct statement: Soap lathers well in soft water.
Universal solvent – Water Pollutant Hard water – Kills germs Boiling – Ozonisation Sterilization – Water Sewage – Stomach ailments
Universal solvent – Water; Water Pollutant – Sewage; Hard water – Kills germs (incorrect match, should be Sterilization); Boiling – Ozonisation (incorrect match); Sterilization – Kills germs; Water – Universal solvent. The correct matches are: Universal solvent – Water, Water Pollutant – Sewage, Sterilization – Kills germs, Boiling – Purification method, and Ozonisation – Water purification method.
1-Mark Questions (MCQ)
Solubility of carbon dioxide in water is high when the ………….
(b) pressure is high
Ch 19Acids and Bases
5-Mark Questions
Write any four physical properties of acids.
Acids are sour in taste, which is one of their most recognizable properties. They are corrosive in nature, meaning strong acids can spoil and damage substances like human skin, clothes, and paper. Generally acids exist in liquid state, but a few acids exist in solid state too, such as benzoic acid and oxalic acid. Acids are typically colorless in their pure form. Acids change the color of indicators, which is a key property used to identify them. Blue litmus paper turns red when treated with acids, and methyl orange turns pink or red in acidic solutions. …
State the difference between acids and bases.
Difference between acids and bases: Acids: They produce H + ions in water. They are sour in taste. Few acids are in solid state. Acids turn blue litmus paper red. Bases: They produce OH – ions in water. They are bitter in taste. Most of the bases are in solid state. Bases turn red litmus paper blue.
2-Mark Questions
Define acid.
An acid is a substance which contains one or more replaceable hydrogen atoms that can be released when the acid reacts with a base or other substances. When dissolved in water, acids ionize to produce hydrogen ions (H⁺), which are responsible for their characteristic sour taste and acidic properties. Common examples of acids include hydrochloric acid, sulfuric acid, acetic acid, and citric acid. Acids are classified as strong or weak depending on the degree to which they ionize in aqueous solution.
What are the similarities between acids and bases?
Acids and bases share several important similarities. Both are corrosive in nature and can damage living tissues and materials. They both undergo ionization in aqueous solution, meaning they break apart into ions when dissolved in water. Both acids and bases conduct electricity in aqueous solution because of the presence of ions. Additionally, both acids and bases undergo neutralization reaction with each other, in which they react to form water and salt, effectively canceling out each other's properties.
What is a neutralization reaction?
A neutralization reaction is a chemical reaction in which an acid and a base react with each other to form water and salt as products. In this reaction, the hydrogen ions from the acid combine with the hydroxide ions from the base to produce water molecules. The remaining ions combine to form a salt. For example, when hydrochloric acid reacts with sodium hydroxide, it produces sodium chloride (salt) and water. Neutralization reactions are important in many practical applications, such as treating acid indigestion with antacids and neutralizing industrial waste.
1-Mark Questions (MCQ)
Acids are ……………. in taste.
(a) sour
Ch 20Chemistry in Everyday Life
5-Mark Questions
Mention the advantages of natural gas.
Natural gas has numerous advantages that make it a valuable energy resource. It produces a lot of heat as it is easily burnt, making it an efficient fuel for generating energy. It does not leave any residue after combustion, which means there is no ash or solid waste to dispose of. Natural gas burns without smoke and therefore causes no air pollution, making it an environmentally friendly fuel compared to coal and other fossil fuels. This can be easily supplied through pipes to homes and industries, making distribution convenient and safe. …
Expand CNG. List out its uses.
CNG stands for Compressed Natural Gas. It is one of the cheapest and cleanest fuels available for use in vehicles and industrial applications. CNG is primarily used as a fuel for automobiles, buses, and trucks, offering significant environmental and economic advantages. Vehicles powered by CNG produce considerably less carbon dioxide and hydrocarbon emissions compared to those running on petrol or diesel, making it an environmentally friendly choice. CNG is also less expensive than both petrol and diesel, which makes it economically attractive for consumers. …
2-Mark Questions
What do you mean by catenation?
Catenation is the property of carbon atoms to form bonds with itself, resulting in the formation of long chains or large structures. This unique ability of carbon to bond with other carbon atoms through single, double, or triple covalent bonds allows it to create an enormous variety of organic compounds. Catenation is one of the most important properties of carbon and is the fundamental reason why carbon forms the basis of all organic chemistry. …
Name the places in Tamilnadu harnessing wind energy from wind mills.
Wind mills are mostly located at Kayathar, Aralvaimozhi, Palladam and Kudimangalam in Tamil Nadu.
1-Mark Questions (MCQ)
The chemical mixed with LPG that helps in the detection of its leakage is …………………
(d) mercapton
Ch 21Crop Production and Management
5-Mark Questions
Define ploughing.
Ploughing, also known as tilling, is an essential agricultural process that involves loosening and turning the soil upward and downward. This mechanical process breaks up compacted soil, making it more friable and workable for crop cultivation. The primary purpose of ploughing is to facilitate the availability and accessibility of nutrients in the root zone of the cultivating crop, allowing plant roots to easily penetrate the soil and absorb essential minerals and water. …
What is foliar spray?
Foliar spray is a technique of feeding plants by applying liquid fertilizer directly to their leaves. This method takes advantage of the fact that plants are able to absorb essential elements and nutrients through the stomata, which are tiny pores present in their leaves. When fertilizers are sprayed on the foliage, the nutrients can be rapidly absorbed through these stomata and transported throughout the plant, providing quick nutrient supplementation. …
2-Mark Questions
Name the methods of sowing.
The different methods of sowing seeds include sowing by hand, using a seed drill, and dibbling. Sowing by hand is the traditional method where seeds are scattered manually across the prepared field. The seed drill is a mechanical device that places seeds at uniform depths and spacing in rows, ensuring better seed placement and reducing seed wastage. Dibbling is a method where individual seeds or groups of seeds are placed in holes made at specific intervals in the soil.
What do you mean by weeding?
Weeding is the process of removing undesirable plants that grow naturally along with crop plants in the field. These undesirable plants are called weeds. Weeds compete with crop plants for water, nutrients, sunlight, and space, which reduces the growth and yield of the main crop. Weeding is an important agricultural practice that helps ensure the crop plants receive adequate resources for healthy growth and better production.
What is crop rotation?
Crop rotation is the agricultural practice of planting a series of different crops in the same field following a defined sequence or order over successive seasons or years. This practice helps to maintain and improve the fertility of the soil by allowing different crops to utilize different nutrients and by allowing the soil to recover. Crop rotation also helps reduce pest and disease buildup in the soil, as different pests and diseases are specific to certain crops. …
1-Mark Questions (MCQ)
The process of placing seeds in the soil is called as ………………..
(b) sowing
Ch 22Conservation of Plants and Animals
5-Mark Questions
Gir national park – Madhya Pradesh Sundarabans National Park – Uttarangal Indira Gandhi National Park – West Bengal Corbett National Park – Gujarat Kanha National Park – Tamil Nadu
Gir national park – Gujarat Sundarabans National Park – West Bengal Indira Gandhi National Park – Tamil Nadu Corbett National Park – Uttarangal Kanha National Park – Madhya Pradesh
What is biosphere reserve?
A biosphere reserve is a protected area designated to conserve biodiversity while allowing sustainable human activities and economic development within its boundaries. The human population also forms an integral part of the biosphere reserve system. These reserves typically cover an area of around 5000 square kilometers or more and are designed to conserve the ecosystem, species, and genetic resources of a region. …
2-Mark Questions
What is global warming?
Global warming is the gradual increase in the average temperature of the Earth's atmosphere caused by the accumulation of greenhouse gases such as methane and carbon dioxide. These gases trap heat energy in the atmosphere, preventing it from escaping into space, which leads to a rise in the overall temperature of the planet. This phenomenon is primarily caused by human activities such as burning of fossil fuels, deforestation, and industrial processes. …
Give few example for extinct species.
Extinct species are organisms that no longer exist on Earth because all members of the species have died. Dinosaurs are examples of extinct species that lived millions of years ago and disappeared due to natural causes. Dodo is another example of an extinct species, a flightless bird that was found in Mauritius and became extinct due to hunting and habitat loss caused by human activities.
Name two endangered animals.
Snow Leo pard Asiatic Lion
1-Mark Questions (MCQ)
The plants found in a particular area are known as …………….
(c) endemic
Ch 23Visual Communication
1-Mark Questions (MCQ)
How many types of page orientation are there in Libre office Writer?
(b) 2
Frequently asked questions
- Name some common systems of measurement.
- There are several common systems of measurement used to express physical quantities. The FPS system uses Foot for length, Pound for mass, and Second for time. The CGS system uses Centimetre for length, Gram for mass, and Second for time. The MKS system uses Metre for length, Kilogram for mass, and Second for time. Among these, the MKS system forms the basis of the International System of Units (SI), which is the most widely used system in science and engineering today. Each system has its own advantages and is used in different contexts depending on the region and field of application. …
- What are the differences between Plane angle and solid angle?
- Plane angle and solid angle are two different types of angles used in geometry and physics. A plane angle is formed by the intersection of two lines or two planes and is two-dimensional in nature. The unit of plane angle is the radian. A solid angle, on the other hand, is formed by the intersection of three or more planes at a common point and is three-dimensional in nature. The unit of solid angle is the steradian. Plane angles are commonly used in two-dimensional geometry and trigonometry, while solid angles are used in three-dimensional geometry, optics, and radiation studies. …
- How many base quantities are included in SI system?
- Seven.
- Give the name of the instrument used for the measurement of temperature.
- The instrument used for the measurement of temperature is a thermometer. A thermometer is a device that contains a liquid (such as mercury or alcohol) or uses electronic sensors to measure the degree of hotness or coldness of a substance or environment. Thermometers work on the principle that liquids or materials expand or contract with changes in temperature, allowing us to read the temperature value on a calibrated scale.
These important questions are selected from the Samacheer Kalvi Class 8 Science textbook book-back exercises to help you revise the most useful questions. Mark weightage (5/2/1) follows the usual exam pattern and may vary by exam — always check your latest syllabus and question pattern. Open each chapter for the complete set of questions and answers.