Term 3 · Class 7 Science · Chapter 4

Samacheer Class 7 Science - Chemistry in Daily Life

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Chapter-wise textbook exercise answers for Chemistry in Daily Life with validation-aware solutions.

Answers marked verified were checked during generation against the chapter context and source question text.
Sections in this chapter
I. Choose the correct answers : 5II. Fill in the blanks : 1III. True or False – If False, give the correct answer : 5IV. Match the following : 1V. Analogy: 1VI. Very short answer : 7VII. Short Answer Questions: 4VIII. Answer in Detail: 2IX. Picture based question 1Activity 1
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1I. Choose the correct answers :5 questions
Q.1A drug effective in the treatment of pneumonia, and bronchitis, is ______v
  1. A. Streptomycin
  2. B. Chloramphenicol
  3. C. Penicillin
  4. D. Sulphaguanidine
Answer:

(c) Penicillin

Q.2Aspirin is ______v
  1. A. Antibiotic
  2. B. Antipyretic
  3. C. Sedative
  4. D. Psychedelic
Answer:

(b) Antipyretic

Q.3______ are that neutralize stomach acid.v
  1. A. Antacid
  2. B. Antipyretic
  3. C. Analgesic
  4. D. Antihistanics
Answer:

(a) Antacid

Q.4The lowest temperature at which a substance catch the fire is called its ______v
  1. A. Boiling point
  2. B. Melting point
  3. C. Critical temperature
  4. D. Ignition temperature
Answer:

(d) Ignition temperature

Q.5Which is the hottest part in the flame of candle ______v
  1. A. Blue
  2. B. Yellow
  3. C. Black
  4. D. Way part
Answer:

(a) Blue

2II. Fill in the blanks :1 questions
Q.G1Penicillin was first discovered by ______ World ORS Day is ______ Combustion is a chemical reaction in which and substance react with ______ In the presence of water, the ignition temperature of paper is ______ Fire produced by oil cannot be controlled by ______v
Answer:

Alexander Fleming
July 29
oxidizing agent
not reached
water

3III. True or False – If False, give the correct answer :5 questions
Q.1Antibiotics does work for viruses like cold andv
Answer:

This statement is false. Antibiotics do not work for viruses like cold and flu. Antibiotics are medicines that kill bacteria or stop their growth, but viruses are different organisms that do not respond to antibiotics. Cold and flu are viral infections, so taking antibiotics for these diseases is ineffective and unnecessary. Using antibiotics when they are not needed can lead to antibiotic resistance, which is a serious public health problem.

Q.2Analgesics are the substances that lower the temperature during fever.v
Answer:

This statement is false. Analgesics are substances that reduce or relieve pain, not lower body temperature. The correct term for substances that lower temperature during fever is antipyretics. Antipyretics work by acting on the body's temperature control center in the brain to reduce fever. It is important to use the correct terminology when discussing medicines and their functions.

Q.3All fuels form flame.v
Answer:

This statement is false. All fuels do not form flame. While many fuels like wood, coal, and candles produce visible flames when they burn, some fuels burn without producing a flame. For example, charcoal can burn with a glow but without a visible flame. A flame is produced only when gases are released during combustion and burn in air, so not all burning fuels necessarily produce flames.

Q.4Oxygen is necessary for combustion.v
Answer:

True. Oxygen is necessary for combustion. Combustion is a chemical reaction that requires three essential elements known as the fire triangle: fuel, heat, and oxygen. Without oxygen, the combustion process cannot occur. This is why fires are extinguished by removing oxygen, such as by using a fire blanket or by displacing air with carbon dioxide or other inert gases.

Q.5Burning wood and coal causes pollution of air.v
Answer:

True. Burning wood and coal causes pollution of air. When wood and coal are burned, they release harmful gases and particles into the atmosphere. These include carbon dioxide, which contributes to climate change, carbon monoxide, which is toxic, and particulate matter that can damage respiratory systems. Burning fossil fuels like coal also releases sulfur dioxide and nitrogen oxides, which contribute to acid rain and smog, making air pollution a serious environmental and health concern.

4IV. Match the following :1 questions
Q.11. Antipyretic Reduce pain 2. Analgesic Reduce body temperature 3. Antacid Spontaneous combustion 4. Phosphorus ORS Solution 5. Carbon – di – oxide Leads to respiratory problemv
Answer:

The correct matching is as follows: Antipyretic substances reduce body temperature during fever by acting on the temperature control center of the brain. Analgesic substances reduce pain and discomfort in the body. Antacid substances neutralize excess acid in the stomach and are used to treat acidity and indigestion, and ORS solution is used to treat dehydration. Phosphorus undergoes spontaneous combustion, meaning it can catch fire on its own at room temperature without an external source of ignition because it has a very low ignition temperature. Carbon dioxide leads to respiratory problems because when inhaled in high concentrations, it can cause difficulty in breathing and other respiratory issues.

5V. Analogy:1 questions
Q.2Tincture:: ______, Histamine : : _______v
Answer:

Antiseptic, Chemical messenger

6VI. Very short answer :7 questions
Q.1First viral disease detected in human being was : _____ (Yellow fever / dengue fever)v
Answer:

Yellow fever.

Q.2______,:_______,:_______ are called green house gasesv
Answer:

CO 2 , Methane, Chlorofluorocarbons

Q.3Name a substance which can be used as an antiseptic as well as disinfectant.v
Answer:

Iodine is a substance that can be used as both an antiseptic and a disinfectant. When used in dilute form, iodine acts as an antiseptic and is applied to wounds and cuts on the skin to prevent infection. In more concentrated forms, iodine can be used as a disinfectant to sterilize surfaces and equipment. Other examples include alcohol and hydrogen peroxide, which can also serve both purposes depending on their concentration and application.

Q.4What are the main constituents of dettol?v
Answer:

The main constituents of Dettol are chloroxylenol and terpineol. Chloroxylenol is the active antimicrobial agent that kills bacteria and other microorganisms, while terpineol is a natural oil that provides a pleasant fragrance and helps in the formulation. These two components work together to make Dettol an effective disinfectant and antiseptic for cleaning wounds and surfaces.

Q.5Name the unit in which the calorific value of a fuel is expressed.v
Answer:

KJ/Kg.

Q.6How many types of combustion are there?v
Answer:

Rapid combustion
Spontaneous combustion
Explosion

Q.7What are the essential requirements for producing fire?v
Answer:

The essential requirements for producing fire are fuel, heat, and oxygen. Fuel is any combustible substance that can burn. Heat provides the initial energy needed to start the combustion process and raise the fuel to its ignition temperature. Oxygen is necessary for the combustion reaction to occur. These three elements together form the fire triangle, and all three must be present simultaneously for fire to be produced and sustained.

7VII. Short Answer Questions:4 questions
Q.1Why should not medicines be taken without consulting doctors?v
Answer:

Medicines should not be taken without consulting doctors for several important reasons. First, a doctor can correctly diagnose the disease and prescribe the appropriate medicine for that specific condition. Taking the wrong medicine for a disease will not cure it and may actually cause harmful side effects to the body. Second, different people may have different allergies, medical conditions, or may be taking other medicines that could interact negatively with a new medicine. Third, the correct dosage is important because taking too much or too little of a medicine can be ineffective or dangerous. Finally, self-medication can lead to antibiotic resistance and other serious health complications. Therefore, it is always essential to consult a qualified doctor before taking any medicine.

Q.2Why do antiseptics differ from disinfectants? Give one example of each.v
Answer:

Difference between Antiseptic and Disinfectants
Antiseptic
Disinfectants
1.
All antiseptic are disinfectants
1. All disinfectants are not antiseptic
2.
It can be applied on the live tissue
2. It can be apply on in animate object
3.
E.g. skin / Mucous
3. E.g. Surface, lab working tables, floor.

Q.3What is ignition temperature?v
Answer:

Ignition temperature is the minimum temperature at which a substance catches fire and burns in the presence of oxygen. Every combustible substance has its own specific ignition temperature. For example, paper has a lower ignition temperature than wood, which is why paper catches fire more easily. When a substance is heated to its ignition temperature, it will spontaneously ignite and continue to burn as long as fuel, heat, and oxygen are available. Different materials have different ignition temperatures, which is why some materials are more flammable than others.

Q.4If 4.5kg of fuel is completely burnt and amount of heat produced stands measured at 1,80,000 KJ. What is the calorific value?v
Answer:

Amount of fuel = 4.5 kg
Heat produced = 1,80,000 kj
Calorific value = ?∴ Calorific value = 40,000 kj/kg

8VIII. Answer in Detail:2 questions
Q.1Explain briefly about antibiotic and analgesic.v
Answer:

Many micro organisms and plants synthesize chemicals which are toxic in nature to protect them from invading organisms.
Those biosynthesized chemicals can be isolated from the plants/micro organisms and was used as medicines against infectious diseases, these substances were called as antibiotics.
Ex: Chloramphenicols, tetracyclines, Penicillin derivatives, cephalosporin’s and their derivatives.
The world’s first antibiotic penicillin was discovered by Dr. Alexander Fleming.
Analgesics:
Analgesics or pain killers that react like the pain-suppressing chemicals released by the body.
They suppress the feeling of ‘pain.
This analgesics drug selectively relieves pain by acting either in CNS (Central Nerves System) or on peripheral pain mechanism, without significantly altering consciousness.

Q.2Make labeled diagram of a candle flame.v
Answer:

9IX. Picture based question1 questions
Q.1Arul and Aakash were doing an experiment in which water was to be heated in a beaker. Arul kept the beaker near the wick in the yellow part of candle flame. Aakash kept the beaker in the outer most part to the flame. Whose water will get heated in a shorter time? v
Answer:

Aakash's water will get heated in a shorter time because he kept his beaker in the outermost part of the flame, which is the hottest non-luminous zone. The non-luminous zone of a candle flame is the region where complete combustion occurs, resulting in the highest temperature. In contrast, Arul kept the beaker near the wick in the yellow luminous part of the flame, which is cooler and produces less heat due to incomplete combustion. The luminous zone appears yellow because of the presence of unburned carbon particles that emit light but do not contribute significantly to heat production. Therefore, the beaker in the non-luminous zone receives more heat energy per unit time, causing the water to reach higher temperatures and boil much faster than the water in the luminous zone.

10Activity1 questions
Q.1What happens when you add with these chemicals? Sugar + Potassium permanganate + Glycerin v
Answer:

After adding sugar, potassium permanganate and glycerin to the dish, immediately step back because spark and solid potassium permanganate will be expelled from the dish.
When potassium permanganate mixes with glycerin, a redox reaction starts. This reaction starts out really slow, but produces a lot of heat, so it will start to speed up bit by bit. As the potassium permanganate oxidises the sugar, it will speed up more and more until it finally starts to smoke and after that it will ignite.