Four moles of hydrogen , two moles of helium and one mole of water vapour form an ideal gas mixture. What is the molar specific heat at constant pressure of mixture?

Options

A. `(16)/(7)R`
B. `(23)/(7)R`
C. `(19)/(7)R`
D. `(26)/(7)R`

Answer

A

Explanation

`C_("pmix") = (n_(1)Cp_(1)+ n_(2)Cp_(2) + n_(3)Cp_(3))/(n_(1) + n_(2) + n_(3))`
=`((4) ((7)/(2)R) + 2 ((5)/(2)R) + 1 (4R))/( 4+ 2 + 1 ) = (23)/(7)R`