In the electrolytic refining of a metal $M$, what would you take as the anode, the cathode and the electrolyte ?

Name two metals which will displace hydrogen from dilute acids, and two metals which will not.

Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.

$(a)$ What will be the action of gas on

$(i)$ dry litmus paper ?

$(ii)$ moist litmus paper ?

$(b)$ Write a balanced chemical equation for the reaction taking place.

What are amphoteric oxides? Give two examples of amphoteric oxides.

Write equations for the reactions of

$(i)$ iron with steam

$(ii)$ calcium and potassium with water