Its density
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.
Yes, diesel will float on top of water. This is because the petrol will weigh less than the water will weigh, therefore it will float on top of the heavier substance.
Objects under water seem to weigh less but they have the same mass as they would out of water.
you would weigh 200 lbs. in water as you would on land. Your body just moved the water out of the way, which explains displacement. Buoyancy is what makes you seem lighter though. Because you weigh more than the water that you displaced and because the the water that you moved has a weight too, your body would be forced up after moving the water out of the way. So it's not that you weigh less in the water if someone picks you up, they just have more help when lifting you.
because there's less water in it.
it is a HOLE.
It makes something weigh more or weigh less. Also it makes something stay in the planet's atmosphere.
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
Less, ovbiously.
Gravitational Pull