Answer:
Part A:
to two significant figures
Part B:
to two significant figures
Part C:
to two significant figures
Explanation:
Given that :
mass of the hydrogen = 0.30 g
the molar mass of hydrogen gas molecule = 2 g/mol
we all know that:
number of moles = mass/molar mass
number of moles = 0.30 g /2 g/mol
number of moles = 0.15 mol
For low temperature between the range of 50 K to 100 K, the specific heat at constant volume for a diatomic gas molecule = 
For Part A:




to two significant figures
Part B. For hot temperature, 




to two significant figures
Part C. For an extremely hot temperature, 




to two significant figures
it depends on the atom . but in some cases it may explode
A: Some physical properties change, but the substance keeps its identity.
Answer:

Explanation:
Using kinematics equations:

Use
due to condition of distance traveled.
Solving second equation for time, there are two solutions. t=0 and

Use the expression in the first equation to have

Using trigonometric identities, you have the answer of the distance.
By doing the ratio for two different angles, you have the second answer. Due to sine function properties, the distances can be the same to complementary angles. Example, for 20° and 70°, the distance is the same.