Question

Why the lower members of aldehyde and ketone are soluble in water while higher members are sparingly soluble or insoluble in water?

Answer 1

Both lower member and higher member contain a highly polar carbonyl group $-CO$, that forms resonably strong bond with water molecular. So, lower members of aldehyde and ketone are miscible with water in all proportion but the solubility decreases as the hydrocarbon chain length increases as hydrocarbon contribute to non-polar part.