Explanation:
Density of the air ,d= 1.189 g/L
(a) Density of the evacuated ball
Mass of the ball ,m = 0.12 g
Volume of the ball =
D<d, teh evacuated ball will flaot in air.
(b) Density of the evacuated ball D = 0.214 g/L
Density of carbon dioxide gas = 
Mass of the carbon dioxide gas :
Total density of filled ball with carbon dioxide gas:
The ball filled with carbon dioxide will not float in the air because total density of filled ball is greater than the density of an air.
(c) Density of the evacuated ball D = 0.214 g/L
Density of hydrogen gas = 
Mass of the hydrogen gas :
Total density of filled ball with hydrogen gas:
The ball filled with hydrogen will float in the air because total density of filled ball is lessor than the density of an air.
(d) Density of the evacuated ball D = 0.214 g/L
Density of oxygen gas = 
Mass of the oxygen gas :
Total density of filled ball with oxygen gas:
The ball filled with oxygen will not float in the air because total density of filled ball is greater than the density of an air.
(e) Density of the evacuated ball D = 0.214 g/L
Density of nitrogen gas = 
Mass of the nitrogen gas :
Total density of filled ball with nitrogen gas:
The ball filled with nitrogen will not float in the air because total density of filled ball is greater than the density of an air.
f) Mass must be added to sink the ball = m
Density of ball > Density of the air ; to sink the ball.
m > 0.54584 g
For any case weight added to ball to make it sink in an air should be grater than the value of 0.54584 grams.
