A gas in an airtight container is heated from 25${}^o$C to 90${}^o$C. The density of gas will :

The density of a gas at N.T.P. is 1.5gm/lit. its density at a pressure of 152cm of Hg and temperature 27${}^0$ C

Two identical containers each of volume V${}_0$ are joined by a small pipe. The containers contain identical gases at temperature T${}_0$ and pressure P${}_0$. One container is heated to temperature 2T${}_0$ while maintaining the other at the same temperature. The common pressure of the gas is P and n is the number of moles of gas in container at temperature 2T${}_0$.