On treatment of 100 mL of 0.1 M solution of CoCl₃. 6H₂O with excess AgNO₃; 1.2 $$\times$$ 10²² ions are precipitated. The complex is :

In the following reactions, ZnO is respectively acting as a/an :

(a) ZnO + Na₂O $$\to$$ Na₂ZnO₂

(b) ZnO + CO₂ $$\to$$ ZnCO₃

The products obtained when chlorine gas reacts with cold and dilute aqueous NaOH are :

A water sample has ppm level concentration of following anions
F^- = 10; $$SO_4^{2-}$$ = 100; $$NO_3^-$$ = 50
The anion/anions that make/makes the water sample unsuitable for drinking is/are :