Question

What is the temperature at which the kinetic energy of $0.3$ moles of helium is equal to the kinetic energy of $0.4$ moles of argon -at $400\, K$ ?

• A. 400 K
• B. 873 K
• C. 533 K
• D. 300 K

Answer 1

Answer: (C)

533 K

Answer 2

Number of moles of helium $=0.3$
Number of moles of argon $=0.4$
We know that $KE = nRT$
$KE$ of helium $=0.3 \times R \times T \ldots$ (i)
$KE$ of argon $=0.4 \times R \times 400 \ldots$ (ii)
According to question
$KE$ of helium $= KE$ of argon
$0.3 \times R \times T=0.4 \times R \times 400$
$T=533\, K$