Answer:
I am round as an apple, deep as a cup. All the King's horses can't pull me up. What am I?
I am often sold by children entrepreneurs in summer time
The more you take away from me the bigger I shall get.
I am the type of room you cannot enter or leave. Raise from the ground below I could be poisonous or a delicious treat.
What is light as a feather but even the strongest man cannot hold it for more than a few minutes?
Give it food and it will live, give it water and it will die.