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Which one of the following reactions does NOT belong to "Lassaigne's test"?
A
$\text{Na} + \text{C} + \text{N} \xrightarrow{\Delta} \text{NaCN}$
B
$2\text{Na} + \text{S} \xrightarrow{\Delta} \text{Na}_2\text{S}$
C
$\text{Na} + \text{X} \xrightarrow{\Delta} \text{NaX}$
D
$2\text{CuO} + \text{C} \xrightarrow{\Delta} 2\text{Cu} + \text{CO}_2$
Explanation
Lassaigne's test involves sodium fusion to convert covalent heteroatoms (N, S, X) into ionic sodium salts (NaCN, $\text{Na}_2\text{S}$, NaX). The reaction with CuO is used in copper oxide test for detection of carbon and hydrogen.
Detailed Solution
In Lassaigne's sodium fusion test, nitrogen, sulphur, and halogens present in an organic compound are converted from covalent to ionic form by fusing with metallic sodium: $\text{Na} + \text{C} + \text{N} \rightarrow \text{NaCN}$, $2\text{Na} + \text{S} \rightarrow \text{Na}_2\text{S}$, and $\text{Na} + \text{X} \rightarrow \text{NaX}$. The reduction of copper(II) oxide ($2\text{CuO} + \text{C} \rightarrow 2\text{Cu} + \text{CO}_2$) is used for the qualitative detection of carbon and hydrogen, not in Lassaigne's test.