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S Block Elements question

2025 · Q93
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S Block Elements question

2025 · Q93

NEETChemistryS Block ElementsMCQ+4 / −1

Which one of the following reactions does NOT belong to "Lassaigne's test"?

  1. A
    Na+X→Δ+NaX\mathrm{Na}+\mathrm{X} \xrightarrow[\Delta]{ }+\mathrm{NaX}Na+XΔ​+NaX
  2. B
    2CuO+C→Δ2Cu+CO22 \mathrm{CuO}+\mathrm{C} \xrightarrow[\Delta]{ } 2 \mathrm{Cu}+\mathrm{CO}_22CuO+CΔ​2Cu+CO2​
  3. C
    Na+C+N⟶ΔNaCN\mathrm{Na}+\mathrm{C}+\mathrm{N} \underset{\Delta}{\longrightarrow} \mathrm{NaCN}Na+C+NΔ⟶​NaCN
  4. D
    2Na+S⟶ΔNa2 S2 \mathrm{Na}+\mathrm{S} \underset{\Delta}{\longrightarrow} \mathrm{Na}_2 \mathrm{~S}2Na+SΔ⟶​Na2​ S
View written solutionFree

Correct answer: B

Nitrogen, sulphur, halogens and phosphorus present in an organic compound are detected by "Lassaigne's test".

$$\begin{aligned} & \mathrm{Na}+\mathrm{C}+\mathrm{N} \xrightarrow{\Delta} \mathrm{NaCN} \\ & 2 \mathrm{Na}+\mathrm{S} \xrightarrow{\Delta} \mathrm{Na}_2 \mathrm{~S} \\ & \mathrm{Na}+\mathrm{X} \xrightarrow{\Delta} \underset{(\mathrm{X}=\mathrm{Cl}, \mathrm{Br}, \mathrm{l})}{\mathrm{NaX}} \end{aligned}$$