It isn't illegal but I think it is unwise. I have sons and neither is eager to do chores, but my wife and I explain to them that contributing to the family home workload is a necessary aspect of being in a family. I would never ask a child to do a chore that I would be unwilling to do myself. Starting out I'd work with the child to demonstrate this. Instead of asking him to "clean up most of the house by himself" I would assign him tasks like making his bed in the morning, putting his dirty clothes in the hamper, loading his own dishes in the dishwasher OR taking one or a couple days of dish washing duty each week, and specific tasks like taking out the trash. Start with simple things and not too much, then build up as he gets older. Be sure to praise him when he does a good job. You might also consider giving him a reasonable allowance for his help.

There is definitely no law against it, but it is important to think what is ethical.  If the boy is stressing, he won't want to do it.  Therefore, he won't want to do it anymore, which will cause you problems in the future, with even small things like picking up his socks after himself.  But I do see that parents don't have time to do all of the cleaning.  Small parts and asking him to do it is much better communication method to use, especially with kids that age.  At this age, you want to start communicating with him, and treating him like an older child just a little bit, so he feels that with age, come responsibilities. Hope this helped!