The value of specific heat at constant volume is 0.723 kJ/kgK, if the density of gas at 27°C and   ${\text{10}}^5{\text{\hspace{0.17em}Nm}}^{\text{-2}}$   is  $1.2{\text{\hspace{0.17em}kg\hspace{0.17em}m}}^{-3}$, what is the specific heat at constant pressure?

detailed solution

Correct option is A

as specific heat at constant volume =cv=0.723 kilo joule/kgK is given  mass of gas is considered, unit doesnot has number of moles of gashence gas equation that need to be considered is PV=mrT ⇒r=PVmT---(1)Pressure is P=105Nm-2density =mass(m)volume(v)=1.2Kgm-3Temperature =27+273 kelvin=300K  substitute above given values in equation (1)r=PVmT=1051.2 x 300=0.2777 kilo joule kg-1K-1  from difference of specific heatscp=cv+r---(2)given cv=0.723 kilo joule/kgK r=0.2777 kilo joule kg-1K-1  substitute above values in (2) equationcp=0.723+0.2777=1.007kJ kg-1K-1