Answer:
Option A, Boyle's law
Explanation:
The complete question is
Pressure and volume changes at a constant temperature can be calculated using
a. Boyle's law. c. Kelvin's law.
b. Charles's law. d. Dalton's law.
Solution
In Boyle’s law, the gas is assumed to be ideal gas and at constant temperature. With these two conditions fixed, Boyle’s established that volume of gas varies inversely with the absolute pressure.
The basic mathematical representation of this phenomenon is as follows -

OR

Where P is the pressure of ideal gas, V is the volume and k is the constant of proportionality.
Hence, option A is correct
No, they usually will not. It also depends why you're going/why you went the first time.
Answer:A
Explanation:
I just did the same question on usatestprep
The efficiency of the engine at the given useful energy and input energy is 28%.
The given parameters:
- <em>Input energy of the engine, = 125 J</em>
- <em>Useful energy of the engine, 35 J</em>
The efficiency of the engine is defined as the ratio of the output energy (useful energy) to the input energy and it is calculated as follows;

Thus, the efficiency of the engine at the given useful energy and input energy is 28%.
Learn more about efficiency of engine here: brainly.com/question/6751595