The following questions consist of two statements- Assertion (A) and reason (R). Answer these questions selecting the appropriate option given below:
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true and R not is the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
1. Assertion (A): Calcium carbonate on heating gives calcium oxide and water.
Reason (R): On heating calcium carbonate, decomposition reaction takes place.
2. Assertion (A): Brown fumes are produced when lead nitrate is heated.
Reason (R): Nitrogen dioxide gas is produced as a by product due to decomposition of lead nitrate. 3. Assertion (A): White silver chloride turns grey in sunlight.
Reason (R): Silver chloride gets burnt in sunlight.
4. Assertion (A): Colour of copper sulphate solution turns green when iron nail is added to it.
Reason (R): Copper is used for making electricity wires.
Answers
Answers
1. (d) A is false but R is true
2. (a) Both A and R are true and R is the correct explanation of A.
3. (c) A is true but R is false.
4. (b) Both A and R are true and R not is. the correct explanation of A.
Explanation
1. Calcium carbonate on heating gives calcium oxide and Carbon dioxide. It is a decomposition reaction.
2. On heating lead nitrate, lead oxide, nitrogen dioxide and oxygen gas are produced. Nitrogen dioxide fumes are reddish brown in colour.
3. White silver chloride turns grey in sunlight as photolytic decomposition reaction takes place and it is decomposed into silver which is grey in colour and chlorine gas. It does not get burnt in sunlight.
4. Colour of copper sulphate solution. turns green when iron nail is added to it as displacement reaction takes place. Iron being more reactive than copper displaces copper from its salt solution. The new solution formed is iron sulphate which is green in colour.
And copper is used for making electrical wires as it is a good conductor of electricity.
Answer:
1. (d) A is false but R is true
2. (a) Both A and R are true and R is the correct explanation of A.
3. (c) A is true but R is false.
4. (b) Both A and R are true and R not is. the correct explanation of A.
Explanation: