Samacheer Class 8 Science - Matter

1I. Choose the best answer7 questions

Q.2The liquid metal used in thermometers is –v

A. Copper
B. Mercury
C. Silver
D. Gold

Solution

(b) Mercury

Answer:

(b) Mercury

Q.3The Pictorial symbol for water given by the alchemists was – Samacheer Kalvi 8th Science Solutions Term 1 Chapter 4 Matter 8

v

Solution

Samacheer Kalvi 8th Science Solutions Term 1 Chapter 4 Matter 11

Answer:

Samacheer Kalvi 8th Science Solutions Term 1 Chapter 4 Matter 11

Q.4Which one of the element name not derived from planet?v

A. Plutonium
B. Neptunium
C. Uranium
D. Mercury

Solution

(d) Mercury

Answer:

(d) Mercury

Q.5Symbol of Mercury is –v

A. Ag
B. Hg
C. Au
D. Pb

Solution

(b) Hg

Answer:

(b) Hg

Q.6A form of non – metal which has high ductility is –v

A. Nitrogen
B. Oxygen
C. Chlorine
D. Carbon

Solution

(d) Carbon

Answer:

(d) Carbon

Q.8The property which allows metals to be hammered into their sheets is –v

A. Ductility
B. Malleability
C. Conductivity
D. Tensile strength

Solution

(b) Malleability

Answer:

(b) Malleability

Q.9The non – metal which conduct current is –v

A. Carbon
B. Oxygen
C. Aluminium
D. Sulphur

Solution

(a) Carbon
8th Science Matter Around Us Book Back Answers Question 10
Pencil lead contains –
(a) Graphite
(b) Diamond
(c) Aluminium
(d) Sulphur
(a) Graphite

Answer:

(a) Carbon
8th Science Matter Around Us Book Back Answers Question 10
Pencil lead contains –
(a) Graphite
(b) Diamond
(c) Aluminium
(d) Sulphur
(a) Graphite

2II. Fill in the blanks1 questions

Q.G1The element which possess character of both metals and non – metals are called …………….. The symbol of Tungsten …………….. Melting point of most metal is …………….. than non – metal. Water contains …………….. and …………….. element. …………….. is the used in semiconductor industry.v

Solution

Metalloids
W
Higher
Hydrogen, oxygen
Silicon / Germanium

Answer:

Metalloids
W
Higher
Hydrogen, oxygen
Silicon / Germanium

3III. True or False, if false correct the statement2 questions

Q.1Metals are generally good conductors of electricity, but not good conductors of heat.v

Solution

False.
Correct statement:
Metals are generally good conductors of heat and electricity.

Answer:

False.
Correct statement:
Metals are generally good conductors of heat and electricity.

Q.2Gallium metal is in solid state at or just above room temperature.v

Solution

False.
Correct statement:
Gallium (Ga) become liquid at or just above room temperature.

Answer:

False.
Correct statement:
Gallium (Ga) become liquid at or just above room temperature.

4IV. Match the substance given in column A with their use given in Column B2 questions

Q.1A B 1. Ironv

(a) For making wires 2. Copper
(b) Sewing needle 3. Tungsten
(c) As a fuel for ignition in rocket. 4. Boron
(d) Making the filament of a bulb

Solution

B
A
D
C

Answer:

B
A
D
C

Q.21. Atom (A) building block of matter 2. Element (B) atoms of different kinds 3. Compound (C) atoms of the same kind 4. Molecule (D) smallest unit of a substancev

A. 1 – A, 2 – C, 3 – B, 4 – D
B. 1 – C,2 – A, 3 – B, 4 – D
C. 1 – D, 2 – C, 3 – B, 4 – A
D. 1 – B, 2 – C, 3 – A, 4 – D

Solution

A
C
B
D

Answer:

A
C
B
D

5V. Very Short Answer Questions8 questions

Q.2Write the constituent elements and their symbols for the following compounds Carbon monoxide Washing sodav

Solution

Compound
Symbols
Constituent elements
Carbon monoxide
(CO)
Carbon and oxygen
Washing soda
(Na 2 CO 3 )
Sodium, carbon and oxygen

Answer:

Compound
Symbols
Constituent elements
Carbon monoxide
(CO)
Carbon and oxygen
Washing soda
(Na 2 CO 3 )
Sodium, carbon and oxygen

Q.3Write the symbols for these elements Oxygen Gold Calcium Cadmium Ironv

Solution

S.No
Element
Symbols
(i)
Oxygen
O
(ii)
Gold
Au
(iii)
Calcium
Ca
(iv)
Cadmium
Cd
(v)
Iron
Fe

Answer:

S.No
Element
Symbols
(i)
Oxygen
O
(ii)
Gold
Au
(iii)
Calcium
Ca
(iv)
Cadmium
Cd
(v)
Iron
Fe

Q.5Which non – metal is essential for our life and all living beings inhale it during breathing?v

Solution

Oxygen is essential for our life and all living beings inhale it during breathing.

Answer:

Oxygen is essential for our life and all living beings inhale it during breathing.

Q.6Why are bells made of metals?v

Solution

On being hit, metals produce a typical sound. They are said to be sonorous. This property is being made used in making bells.

Answer:

On being hit, metals produce a typical sound. They are said to be sonorous. This property is being made used in making bells.

Q.7What does a chemical symbol represent?v

Solution

A chemical symbol is a shorthand method of representing an element.
Symbol of an element signifies:
Name of the element.
One atom of the element for example,
The symbol O stands for the element of oxygen.
One atom of oxygen.

Answer:

A chemical symbol is a shorthand method of representing an element.
Symbol of an element signifies:
Name of the element.
One atom of the element for example,
The symbol O stands for the element of oxygen.
One atom of oxygen.

Q.8Give two examples for metalloids.v

Solution

Boron and silicon.

Answer:

Boron and silicon.

Q.9Mention any three compounds that exist in liquid state.v

Solution

Water
Hydro chloric Acid
Nitric Acid

Answer:

Water
Hydro chloric Acid
Nitric Acid

Q.10Write three properties of metalloids.v

Solution

Properties of metalloids:
Metalloids are all solid at room temperature.
They can form alloys with other metals
Some metalloids, such as silicon and germanium, can act as electrical conductors under the specific conditions, thus they are called semiconductors.
Silicon for example appears lustrous, but is not malleable nor ductile (it is brittle – a characteristic of some non – metals). It is a much poorer conductor of heat and electricity than the metals

Answer:

Properties of metalloids:
Metalloids are all solid at room temperature.
They can form alloys with other metals
Some metalloids, such as silicon and germanium, can act as electrical conductors under the specific conditions, thus they are called semiconductors.
Silicon for example appears lustrous, but is not malleable nor ductile (it is brittle – a characteristic of some non – metals). It is a much poorer conductor of heat and electricity than the metals

6VI. Samacheer Kalvi Guru Science Short Answer Questions7 questions

Q.1Can you store pickle in an aluminium utensil? Explain.v

Solution

No, we cannot store the lemon pickle in aluminium utensil because aluminium is a metal and lemon is acidic. The acids react with metals to give hydrogen which would spoil the food and makes it unfit to use.

Answer:

No, we cannot store the lemon pickle in aluminium utensil because aluminium is a metal and lemon is acidic. The acids react with metals to give hydrogen which would spoil the food and makes it unfit to use.

Q.4Why are utensils made up of aluminium and brass?v

Solution

The cooking utensils are made up of aluminium and brass because they are good conductors of heat.
Aluminium will form a layer of protective oxide that prevents further reaction. Also aluminium is also relatively cheap and that is why it is used widely in making utensils.

Answer:

The cooking utensils are made up of aluminium and brass because they are good conductors of heat.
Aluminium will form a layer of protective oxide that prevents further reaction. Also aluminium is also relatively cheap and that is why it is used widely in making utensils.

Q.5Define a Alchemy.v

Solution

Alchemy was form of chemistry studied in the middle age, which was concerned with trying to discover ways to change ordinary metals into gold.

Answer:

Alchemy was form of chemistry studied in the middle age, which was concerned with trying to discover ways to change ordinary metals into gold.

Q.6Name the elements for following symbols. Na W Ba Al Uv

Solution

Na – Sodium
W – Tungsten
Ba – Barium
Al – Aluminium
U – Uranium.

Answer:

Na – Sodium
W – Tungsten
Ba – Barium
Al – Aluminium
U – Uranium.

Q.7Name six common non – metals and write their symbols.v

Solution

S.No
Non – metals
Symbols
1.
Sulphur
S
2.
Carbon
c
3.
Oxygen
0
4.
Hydrogen
H
5.
Helium
He
6.
Nitrogen
N

Answer:

S.No
Non – metals
Symbols
1.
Sulphur
S
2.
Carbon
c
3.
Oxygen
0
4.
Hydrogen
H
5.
Helium
He
6.
Nitrogen
N

Q.9Mention the metals that are used in jewellery.v

Solution

Silver and gold are used for making jewels and in decorative purposes

Answer:

Silver and gold are used for making jewels and in decorative purposes

Q.10Mention the uses for the following compounds. Baking soda Bleaching powder Quick limev

Solution

S.No
Compounds
Uses
(i)
Baking soda
Fire extinguisher, preparation of baking powder and preparation of cakes and bread.
(ii)
Bleaching powder
As bleaching agent, disinfectant and sterilisation of drinking water.
(iii)
Quick lime
Manufacture of cement and glass.

Answer:

S.No
Compounds
Uses
(i)
Baking soda
Fire extinguisher, preparation of baking powder and preparation of cakes and bread.
(ii)
Bleaching powder
As bleaching agent, disinfectant and sterilisation of drinking water.
(iii)
Quick lime
Manufacture of cement and glass.

7VII. Reason out1 questions

Q.2Why wires cannot be drawn from materials such as stone or wood?v

Solution

Wires cannot be drawn from materials such as stone or wood, is because these materials are non – conductors of electricity.

Answer:

Wires cannot be drawn from materials such as stone or wood, is because these materials are non – conductors of electricity.