We have that all (ideal) gases obey the fundamental gas equation: PV=nRT where P is the Pressure, V is the Volume, n is the number of moles, R is a universal constant and T is the temperature in Kelvin. In this process, we have that both the number of moles and the temperature stays the same. So if we denote by i the initial conditions and by f the final conditions of the gas, we have:

. Hence, if we solve for the final Volume we get:

. Now we know all the other variables; substituting we get that the final volume is 6.7 L (6.716 L ).
2-naphthol, based on its structure will be least soluble in water.
2-Naphthol, or β-naphthol, is a fluorescent, colorless (or occasionally yellow) crystalline solid with the formula C10H7OH. It is an isomer of 1-naphthol, differing by the location of the hydroxyl group on the naphthalene ring. The naphthols are naphthalene homologues of phenol, but more reactive. Both isomers are soluble in simple alcohols, ethers, and chloroform. 2-Naphthol is a widely used intermediate for the production of dyes and other compounds.