Answer:
Option (c) 
Explanation:
Here, it is required to describe the given length in a particular unit. Firstly, we need to see the following conversions as :
1 meter = 0.001 kilometers
1 meter = 10⁻⁶ megameters
1 meter = 1000 millimeters
1 meter = 1000000 micrometers
From the given option, the correct one is (c) because, 1 meter = 1000 millimeters
So, 
Hence, the correct option is (c). Hence, this is the required solution.
Answer:
B. A object in motion stays in motion, and an object at rest stays at rest unless acted upon by a net force.
A sound wave is a wave of compression and rarefaction, by which sound is propagated in an elastic medium such as air.
Momentum before the hit:
p = mv = 0.01 * 300 + 1 * 0
Momentum after the hit:
p = 0.01 * 150 + 1 * v
Momentum is conserved:
0.01 * 300 = 0.01 * 150 + v
3 = 1.5 + v
v = 1.5
The velocity of the block after the collision is 1.5 m/s.