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JEE Main levelOne or more correct optionsDifficulty 2 of 3td010

At $300 K$ , treating all gases as ideal, which of the following statements is/are correct?

AFor $2 H X_{2} (g) + O X_{2} (g) 2 H X_{2} O (l)$ , $Δ H < Δ U$ .
BFor $CaCO X_{3} (s) CaO (s) + CO X_{2} (g)$ , $Δ H - Δ U = RT$ .
CFor $H X_{2} (g) + I X_{2} (g) 2 HI (g)$ , $Δ H = Δ U$ .
DFor $C (graphite) + O X_{2} (g) CO X_{2} (g)$ , $Δ H - Δ U = RT$ .

Answer: A, B, C

Use

Δ H - Δ U = Δ n_{g} RT

. (A)

Δ n_{g} = 0 - 3 = - 3

, so

Δ H < Δ U

: true. (B)

Δ n_{g} = + 1

: true. (C)

Δ n_{g} = 2 - 2 = 0

: true. (D)

Δ n_{g} = 1 - 1 = 0

, so

Δ H = Δ U

, not

RT

: false.

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