Cold and dilute HNO₃ reacts with Cu to give :

1. NO₂
2. NO
3. N₂
4. O₂

The brown ring test is used for the detection of :

1. CO₃^2-
2. Cl^-
3. NO₃^-
4. SO₃^2-

The solvent for NO is :

1. Freshly prepared FeSO₄
2. Fe₂(SO₄)₃
3. FeCl₃
4. FeCl₂

The acid which can be used to etch designs on brassware is :

1. HCl
2. HNO₃
3. H₂SO₄
4. H₂CO₃