Question

Nitrogen dioxide cannot be obtained by heating:

• A. $KN{O}_3$
  
• B. $LiN{O}_3$
• C. $RbN{O}_3$
  
• D. $NaN{O}_3$

Answer 1

Answer: (A), (C), (D)

The correct options are
A $KN{O}_3$

C $RbN{O}_3$

D $NaN{O}_3$

Alkali nitrate on heating decompose to give respective nitrite and $O_2$. But Lithium metal is an exception for this.
Lithium nitrate on heating decompose to give lithium oxide, nitrogen dioxide and oxygen because $L{i}^{+}$ ion has high polarising power which favour the formation of oxide.
$4LiN{O}_3\to 2L{i}_{2}O+4N{O}_2+O_2$
$2MN{O}_3\to 2MN{O}_2+O_2$
where, M = Na, K and Rb.
Hence, (a), (c) and (d) are correct.