An object of mass 2 kg travels through outer space in a straight line at a constant speed of 100 m/s. One may most correctly conclude that
a. It is subject to no forces
b. It is subject to a net force of zero
c. It is being propelled by a constant net force
d. It must have been pushed by a force of 50 N

b. It is subject to a net force of zero

Explanation:

F = m*a

F = force

m = mass

a = acceleration

Since the object is moving at a constant velocity not speeding up or slowing down and moving in a sight line. All the forces that are acting on the object are canceling each other out so the answer is:

b. It is subject to a net force of zero

float.

archimedes' principle

denser than water sinks in water.

denser than mercury would sink in it