Given:
1 cubic meter of hot air can lift about 0.25 kg
We can solve this question by unity method as shown below:
0.25 kg can be lifted by air = 1 cubic meter
1 kg can be lifted by air = 1/0.25 = 4 cubic meter or air
So,
500 kg can be lifted by = 4 x 500 = 2000 cubic meter of air