Question

A metal gives lilac colour in bunsen flame and the solution of its oxide turns red litmus paper blue. The metal is?

• A. $Na$
• B. $K$
• C. $Ca$
• D. $Li$

Answer 1

Answer: (B)

Potassium metal ($K$) gives lilac (pink) colour in bunsen flame. Its oxide dissolves in water to form potassium hydroxide, which is an alkali. So, the solution of its oxide turns red litmus paper blue.

$K_{2}O+H_{2}O\to 2KOH$

Sodium metal ($Na$) gives yellow flame, calcium ($Ca$) gives orange red flame and lithium ($Li$) gives red flame.