Answer: Total volume of fat in his body is 
Explanation:
Density is defined as the mass contained per unit volume.

Given:
Density of fat cells = 
mass of fat cells = 20% of the mass of a 70 kg student's body is fat= 
Volume of fat = ?
Putting in the values we get:


Thus total volume of fat in his body is 
Answer:
Barbell squat
Explanation:
Squatting is a type of workout that focuses on the hips, glutes, and legs. Here, a person stands with feet apart, arms kept close together then goes down and comes up again.
The barbell squat is a type of squatting variation where a person uses a barbell to squat for increased weight in addition to his own body weight with his shoulder supporting the barbell.
Therefore, for the person to keep shoulders down and together throughout the entire movement would probably be doing a barbell squat.