Both these sentences are correct, but they sound very unnatural. In modern everyday English, we very rarely use 'much' in positive statements. Here are some alternatives: Informal: I spend a lot of time on my homework. More formal: I spend a great deal of time on my homework.

much is usually used in a negative sense only so you can't use it for either of these sentences. Use 'a lot' when you're talking about something that isn't bad. I spend *too* much time on homework. --> too much is a negative feeling I spend a lot of time on homework. --> a lot of is neutral (not positive or negative)