Pls help Qn 9,10,11

Qn 11
Answers,
a) 10g/cm3
b) 20g/cm3
c) 30g/cm3
d) 40g/cm3

Ahot-air balloonist, rising vertically with a constant speed of 5.00 m/s releases a sandbag at the instant the balloon is 40.0 m above the ground. after it is released, the sandbag encounters no appreciable air drag. compute the velocity of the sandbag at 0.250 s after its release.

How will the system respond to a temperature increase?

Sound is a disturbance that travels through a medium as a