A $10 L$ vessel at $300 K$ contains $H X_{2}$ at partial pressure $2.0 atm$ and $Cl X_{2}$ at partial pressure $1.0 atm$ . The gases react completely to form $HCl (g)$ and the vessel is returned to $300 K$ . Which statements are correct?

Answer: A, B, C, D

H X_{2} + Cl X_{2} 2 HCl

, 1 : 1, so

Cl X_{2}

(1.0 atm) is limiting (A). It consumes

1.0 atm

H X_{2}

and forms

2.0 atm

HCl

(C). Left:

H X_{2}

1.0 atm

(D). Total

= 1.0 + 2.0 = 3.0 atm

, unchanged because moles of gas are conserved (B).