To test if the hypothesis is correct, a good way is to think of it this way:
Density = mass/volume, right?
Calculate the mass and volume of each and do the equation; this will test your hypothesis.
You will be left with the density of each. But, make sure that the sample sizes are the same (controlled variable) otherwise it will be an unfair test.
<u>Answer:</u> The pressure of NO and
in the mixture is 0.58 atm and 0.024 atm respectively.
<u>Explanation:</u>
We are given:
Equilibrium partial pressure of
= 0.29 atm
For the given chemical equation:

Initial: a
At eqllm: a-2x 2x x
Calculating for the value of 'x'

Equilibrium partial pressure of NO = 2x = 2(0.29) = 0.58 atm
Equilibrium partial pressure of
= a - 2x = a - 2(0.29) = a - 0.58
The expression of
for above equation follows:

We are given:

Putting values in above expression, we get:

Neglecting the value of a = 0.555 because it cannot be less than the equilibrium concentration.
So, 
Equilibrium partial pressure of
= (a - 0.58) = (0.604 - 0.58) = 0.024 atm
Hence, the pressure of NO and
in the mixture is 0.58 atm and 0.024 atm respectively.
the mass of a carbon atom is 1.994 x 10⁻²³ g
the mass of the carbon sample is 12.01 g
to find the number of Carbon atoms we have to divide the mass of sample by mass of a carbon atom.
number of C atoms =

therefore number of atoms = 6.023 X 10²³ atoms of carbon
B. Intake valve is the correct answer
Radioactivity or radioactive decay is the process that occurs when unstable isotopes or atoms release energy by emitting radiations such as ,gamma radiations, alpha radiations and beta radiations to attain stability. Therefore, in this case decay is likely to occur when a given atom has two many neutrons in its nucleus in order to attain stability.