B
A qualitative observation describes the characteristics of a substance without quantifying them.
FeS is an example of an ionic compound as in the formula there is a metal of Fe iron chemically bonded to the nonmetal S sulphur. Resulting in a strong electrostatic attraction due to the transfer of valence electrons from the iron to the Sulphur.
An increase in the number of gas molecules in the same volume container increases pressure. A decrease in container volume increases gas pressure. An increase in temperature of a gas in a rigid container increases the pressure.
