Answer:
The sound intensity of train is 1000 times greater than that of the library.
Explanation:
We have expression for sound intensity level,

A train whistle has a sound intensity level of 70 dB
We have

A library has a sound intensity level of about 40 dB
We also have

Dividing both equations

The sound intensity of train is 1000 times greater than that of the library.
Answer: A. Work is done on the system and heat is transferred from the system for a net decrease in internal energy.
Explanation:
A refrigerator is a device which dispenses heat from the close system to a warmer area or in the surrounding. By dispensing the heat the internal temperature of the refrigerator drops. The system of refrigerator violates the second law of thermodynamics. As it performs the work to cool the region instead of heating the region. The work is done on the system and the internal energy decreases and the heat energy is liberated to the surrounding area. A refrigerator is an open system.
To provide a greater certainty that the observed results are not by chance.
Number of barrels are 3.0. Each barrel contains 42 gallons of oil. Thus, total volume of oil will be 42×3=126 gallons.
Converting gallons into m^{3}
1 gallon=0.00378 m^{3}
Thus, 126 gallons=0.4769 m^{3}
Thickness of oil film is 2.5\times 10^{2} nm, converting it into meters as follows:
1 nm=10^{-9} m
Thus,
2.5\times 10^{2} nm=1.5\times 10^{-7}m
Now, volume V of oil is related to area A and thickness T as follows:
V=A×T
rearranging,
A=\frac{V}{T}=\frac{0.4769 m^{3}}{2\times 10^{-7}m}=2.38\times 10^{6}m^{2}
Thus, square meters of oil will be 2.38\times 10^{6}m^{2}