An element occupies group number 1 and period number 3. This element when exposed to air gives compound (A). The element with water forms compound (B). Which is a strong base und (A) with ammonia gives compound (C ) which is used as reducing agent in organic chemistry. The element reacts with an halogen and forms cooking salt (D). Identify A, B, C and D.

Explanation

(i) An element beonging to group number 1 and period number 3 is sodium.
(ii) sodium when exposed air give sodium peroxide (A).
`4Na+O_2tounderset((A))2Na_2O_2`
(iii) With water sodium forms sodium hydroxide (B)
`2Na+2H_2Otounderset((B))2NaOH+H_2`
(iv) With ammonia, sodium gives sodamide (C )
`2Na+2NH_3overset(570-670K)tounderset((C ))2NaNH_2+H_2`
(vi) Sodium, on reaction wiht a halogen `(Cl_2)` forms sodium chloride (D)
`2Na+Cl_2tounderset((A))2NaCl`