Two non-metallic gaseous elements react in 1 : 3 ratio to give another gas X. A mixture of X and oxygen is taken in a jar and a burning match stick is introduced into it. Another sample of the same mixture containing large excess of `O_(2)` is passed over heated platinum. The mixture of gaseous products is dissolved in water to give Y and Z which are colourless. Z on long standing turns to yellow. Identify X, Y and Z by giving reasons wherever necessary. Also identify the exothermic reaction in the above sequence.

Explanation

(i) identification of the acid which turns to yellow on long standing
(ii) identification of X
(iii) products obtained in the two jars
(iv) comparison of reactivity of products in the respective jars with water
(v) products obtained
(vi) identification of Y and Z