Question

A good source of energy would be the one which would do a ___________ amount of work per unit volume of mass. Any source of energy we used to do work is consumed &_______used again.
A. Larger, can be
B. Smaller, can be
C. Larger, cannot be
D. Smaller, cannot be

Answer 1

Hint: A good source of energy mainly depends on the calorific value of the energy source, easy accessibility of the goods, storage, safety and convenience of its usage. It should be efficient and easy to handle. From these concepts, we can formulate the functions of good fuel.

Complete step-by-step answer:
The main characteristics of a good source of energy are, it should do a large amount of work per unit volume or mass. The first law of Thermodynamic states that the energy can be neither created nor destroyed it can be converted from one form to another. For a good source of energy, the work per unit volume or mass has to be higher; it indicates that the output energy must be higher than the input energy. Therefore, it should have a high calorific value.
Sources of energy have to be easily accessible and it should have the capacity to serve for a longer time. The easily vanishing source of energy cannot be categorized to a good source. The energy sources such as coal, petroleum, gas, LPG are forms of a good source of energy. Their transport from the point of production to consumer, its storage and safety of using all these factors makes them a good source of energy.
Even though they have high calorific value, most of the fuels are not reusable. The useful energy will convert from one form to another form. So, when we consumed fuel, it cannot be used again.
A good source of energy would be the one which would do a larger amount of work per unit volume of mass. Any source of energy we used to do work is consumed & it cannot be used again.
Therefore, Option C is the correct option.

Note: The factors influencing a good source of energy have to be kept in mind to answer the question correctly without any confusion. Do not think good fuels that we are using have reusable property. That is a wrong concept. Even the Carnot engine is an ideal concept. Like this, fuels that can be used again is an ideal concept. Maybe some of the fuels can turn into another type of fuels. But eventually, it will be over and produce effective energy or work.