Question

An element occupies group number 1 and period number 3. This element heated in air gives compound A. With water it gives compound B - a strong base. With ammonia gives compound C, which is used as a reducing agent in organic chemistry. Identify the element A,B and C. 

Answer 1

(i) As per the position in the periodic table this element occupying group number 1 and period number 3 is sodium. 

(ii) When heated in air, it forms sodium peroxide (A) 

 4Na + O₂ → 2Na₂O₂

(iii) With water, sodium gives sodium hydroxide (B) 

2Na + 2H₂O → 2NaOH + H₂

(iv) With ammonia, sodium gives sodamide (I)

The element is sodium. 

The compound A is sodium peroxide. 

The compound B is sodium hydroxide. 

The compound C is sodamide.