An element A burns with golden flame in air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved. 

Explanation

A is sodium (Na) because it butms with golden flame in air.
B is chlorine (Cl) as its atomic number is 17. When nNa reacts with `Cl_(2)`,NaCl is formed.
Hence, C is sodium chloride (NaCl).
`underset((A))(2Na(s))+underset((B))(Cl_(2)(g))tounderset((C))(2NaCl(s))`
Aquepus sodium of NaCl, on electrolysis gives sodium hydroxide.
Thus, D sodium hydroxide (NaOH).
`underset((C))(2NaCl(aq))+underset((B))(2H_(2)O(l))overset("Electrolysis")tounderset((D))underset("hydroxide")underset("Sodium")(2NaOH(aq))+Cl_(2)(g)+H_(2)(g)`