Entropy is the measure of the amount of disordered in a system.
<u>Explanation:</u>
In 1850, Entropy introduction by the German physicist Rudolf Clausius refers a measurement of the system's thermal energy in unit temperature. It is not for useful work because the work originates from ordered molecular motions. And, this also measures the molecular disturbance or randomness of the system.
The concept behind this provides deep view into spontaneous changes in many everyday phenomena’s. The idea of entropy is a mathematical way of coding an intuitive idea whose processes are impossible, and not violate the basic principle of energy conservation.
Answer:
B. The presence of an unbalanced force(e.g friction) causes a moving object to stop.
Explanation:
As the friction is that force that can stop the sled upon reaching the levelled surface so the option b is correct.