State the original colour of the following substances and colour of residue obtained after heating.

(a) ammonium dichromate

(b) copper carbonate

(c) lead nitrate

(d) zinc carbonate

Carbon dioxide and sulphur dioxide gas can be distinguished by using :

(a) moist blue litmus paper

(b) lime water

(c) acidified potassium dichromate paper

(d) none of the above

Assertion (A): Glass rod dipped in NH₄OH gives dense white fumes with HCl gas.

Reason (R): HCI gas is acidic in nature.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Assertion (A): Zinc nitrate on heating produces a colourless gas, brown gas and yellow residue which fuses with the glass.

Reason (R): Zinc nitrate decomposes to give ZnO, NO₂ and O₂.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.