Question

Difference in the molecular weight of formaldehyde compared to similar compounds—How does this difference affect properties (e.g., solubility) to change the range of uses?

Answer 1

Formaldehyde is the smallest possible aldehyde, and as we increase the molecular weight then non-polar hydrocarbon part increase and as we know non-polar hydrocarbons are almost insoluble in the polar solvent like Water and thus we can say that solubility decrease with rise in the molecular weight.  

Increase in molecular weight cause increase in intermolecular force of attraction thus boiling point and melting point increases with increase in the molecular weight.