Stability of Conformations

Q. A flask filled SO2(g) was weighed at a temperatureand pressure. The same flask was then filled withCH (g) at the same temperature and pressure. Themass of SO2(g) would be about(1) The same as that of the methane(2) One-fourth as heavy as methane(3) 4 times as heavy as methane(4) Twice as heavy as methane

Q. Which conformer of the compound given below is the most stable?
$HO-C{H}_2-C{H}_2-F$

1. Staggered
2. Partially eclipsed
3. Gauche
4. Fully eclipsed