Electrons are valence and free moving so they take place in charge transfer
The specific heat capacity the substance is calculated using the below formula
Q(heat) = Mc delta T
Q =1560 cal
m(mass) 312 g
delta T (change in temperature ) = 15 c
C= specific heat capacity=?
by making c the subject of the formula
c=Q/m delta T
= 1560 cal/ 312g x 15 c = 0.33 cal/g/c (answer B)
Cl2=3.17g/L
Ne=.901g/L
CO2=1.96g/l
therefore Cl2 is the densest gas under the given conditions.