The number of endothermic process/es from the following is ______ A. $\mathrm{I}_{2}(\mathrm{g}) \rightarrow 2\mathrm{I}(\mathrm{g})$ B. $\mathrm{HCl}(\mathrm{g}) \rightarrow \mathrm{H}(\mathrm{g})+\mathrm{Cl}(\mathrm{g})$ C. $\mathrm{H}_{2}\mathrm{O}(\mathrm{l}) \rightarrow \mathrm{H}_{2}\mathrm{O}(\mathrm{g})$ D. $\mathrm{C}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}(\mathrm{g})$ E. Dissolution of ammonium chloride in water

JEE Main · 2023 · 10 Apr 2023 · Shift 2 · Chemical Thermodynamics

The number of endothermic process/es from the following is ______
A.

I_{2} (g) \to 2 I (g)

HCl (g) \to H (g) + Cl (g)

H_{2} O (l) \to H_{2} O (g)

C (s) + O_{2} (g) \to CO_{2} (g)

E. Dissolution of ammonium chloride in water

Answer: 4

Solution

Breaking the

I - I

bond of

I_{2} (g)

and the

H - Cl

bond of

HCl (g)

both absorb energy, so A and B are endothermic. Vaporising water in C absorbs its latent heat of vaporisation, so it is endothermic. Dissolving ammonium chloride cools the solution, so E is endothermic. Only the combustion of carbon in D releases heat and is exothermic. The number of endothermic processes is 4.

JEE Main · 2023 · 10 Apr 2023 · Shift 2 · Integer answer

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