Page 58 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

4. Which reaction takes place when water is added to calcium chloride?

(a) Exothermic reaction
(b) Endothermic reaction
(c) Calcium carbonate does not react with water

(d) None of the above
Ans. (a)
5. The substances that participate in a chemical reaction are called ................... .

(a) Reactants (b) Products
(c) Both (a) and (b) (d) Chemical substances

Ans. (a)
B. Fill in the blanks.
1. A change in which a new substance with different properties is formed is known as

................... .
Ans. chemical change

2. Freezing of water is a ................... change.
Ans. physical
3. Setting of curd is a ................... process.

Ans. chemical
4. To prevent rusting of iron benches in gardens, they are ....................... .
Ans. galvanised, alloyed etc.

5. The burning of candle is a ................... as well as a chemical change.
Ans. physical
C. State whether the following statements are true (T) or false (F).

1. Formation of manure from leaves is a physical change.
2. Iron and rust are same substances.

3. Most of the chemical changes are permanent.
4. Lime water turns milky when hydrogen gas is passed through it.
5. Mixing of powdered sulphur with iron filings is a chemical change.

6. One or more new substances are formed in a chemical change.
Ans. 1. (F) 2. (F) 3. (T) 4. (F) 5. (F) 6. (T)

D. Match the following.
Column A Column B
1. Depositing a layer of zinc on iron (a) Turns lime water milky

2. Souring of milk (b) Physical change
3. Carbon dioxide (c) Rust
4. Iron oxide (d) Chemical change

5. Dissolving common salt in water (e) Galvanisation
Ans. 1. (e) 2. (d) 3. (a) 4. (c) 5. (b)

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