Answer:
Final temperature, 
Explanation:
Given that,
Mass of silver ring, m = 4 g
Initial temperature, 
Heat released, Q = -18 J (as heat is released)
Specific heat capacity of silver, 
To find,
Final temperature
Solution,
The expression for the specific heat is given by :





So, the final temperature of silver is 21.85 degrees Celsius.
The correct answer to the question is : 1) Converting energy and 2) Within about twenty years, natural gas forms.
EXPLANATION:
In coal fired power plants, the water is heated by burning coals. The heat produced in this process will convert water into steam. The steam is allowed to rotate the turbine. The turbine is attached to a generator which converts the kinetic energy of the steam into electric energy due to electromagnetic induction.
Hence, turbine helps in converting energy.
As per the second question, Walt listed the steps that occur during the formation of natural gas.
The natural gas is produced due to natural phenomenon. For this, millions of years are passed. So, it is a long range process in which the fossil of animals and planets buried beneath the surface are converted into natural gas under high pressure.
Hence, the mistake of Walt is that the natural gas is produced withing twenty years.
Necrosis - the death of most or all of the cells in an organ or tissue due to disease, injury, or failure of the blood supply.
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Earth's gravity is stronger at the poles than the equator for two reasons: The centrifugal "force" cancels out the gravity minimally, more so at the equator than at the poles.