From the formulae listed in the box, choose one in each case corresponding to the salt having the given description:
`AgCl,CuCO_(3),CuSO_(4)*5H_(2)O,KNO_(3),NaCl,NaHSO_(4),Pb(NO_(3))_(2) ,
(i) an acid salt
(ii) an insoluble chloride
(iii) on treating with concentrated sulphuric acid, this salt changes from blue to white.
(iv) on heating, this salt changes from green to black.
(v) this salt gives nitrogen dioxide on heating.

Explanation

To solve the question, we will analyze each description provided and match it with the appropriate salt from the list given.

### Step-by-Step Solution:

1. **Identify an acid salt:**
- An acid salt is a salt that contains an ionizable hydrogen atom. From the list, the salt that fits this description is **NaHSO₄** (Sodium hydrogen sulfate).

**Answer:** NaHSO₄
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