You haven't said "more or less" than what.
He weighs more than a beach ball and less than a manatee.
Everybody weighs less in water than they do out of it. But every person weighs
more than some other people and less that some other other people, whether
any of them are in or out of the water.
More
No, just because a human is in water, doesn't mean they will weigh less. Humans would weight the same if they were in pudding, so humans do not weigh less in water.
Objects under water seem to weigh less but they have the same mass as they would out of water.
because there's less water in it.
yes
no
No. Oil is less dense than water, so 1 liter of oil will weigh less than 1 liter of water.
because there is less gravity in water
the person will weigh less because of the buoyant force acting upwards, depending upon the volume of water displaced by the person.
Less, ovbiously.
Because sea water is more dense than regular water
An average person would weigh 6 times less than their actual weight.