If a reaction is carried out in a protic solvent, whose molecules have a hydrogen bonded to an oxygen or to a nitrogen, the larger atom is a better nucleophile in an S_N2 reaction. In other words, the weaker base is the better nucleophile in a protic solvent. For example, the iodide ion is better than a fluoride ion as a nucleophile. However, if the reaction is carried out in an aprotic solvent, whose molecules do not have hydrogen bonded to an oxygen or to a nitrogen, then the stronger base is the better nucleophile. In this case, the fluoride ion is better than the iodide ion as a nucleophile.

Can u please explain this statement and why this is true???

Actually the statement means that the liquid in glass thermometer shall show different readings,with different liquids,due to differences in various properties like Viscosity and Coefficient of Thermal Expansion.

While on the other hand,in gas thermometers we try using the properties of expansion of gases,to find the temperature and which overall is same for all gases(assuming they are ideal).V is directly prop.to T and hence u can say that gases(ideal Gases) expand on increase of temperature.

The pressure exerted by 12g of an ideal gas at temperature t degrees C,in a vessel of volume V litre is 1 atm.when temperature is increased by 10 degrees at same volume,pressure increases by 10%.Calculate t and V(molecular wt. of gas=120).