Which of the following represents the correct order of reactivity of metals?

Which medicine is prepared using ammonia?

Stainless steel is a very useful material in our daily life. In stainless steel,iron is mixed with:

$(a)$ $A$ substance $X$,an oxide of a metal,is used extensively in the cement industry. This element is found in our bones also. On treatment with water,it forms a solution which turns red litmus blue. Identify $X$ and also write the chemical reaction involved.
$(b)$ Choose a metal from the following metals which reacts only with hot water: Sodium,magnesium,iron. Mention the products formed during the reaction.

Name two metals which are purified by electrolytic refining. Mention the anode,cathode and the electrolyte used in the refining process. At which electrode would the pure metal be deposited?

Which of the following is not a metalloid?