Which gas sample contains the most molecules ?

CO2

Explanation:

(a) CO2; according to Avogadro's Hypothesis, they all contain the same number of particles, therefore, the heaviest molecule, CO2 (molar mass = 44), will have the greatest mass. (b) all the same; at the same temperature all gases have the same kinetic energy.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.