I think the answer is A. breaks rocks apart.
One mole is always the same number: 6.02 * 10^ 23.
So, one mole of cars = 6.02 * 10 ^23 cars; one mole of pencils = 6.02 * 10^23 pencils; one mole of atoms = 6.02 * 10^23 atoms; one mole of molecules = 6.02 * 10^23 molecules.
So, all the options are correct: one mole of calcium ions has 6.02 * 10^23 representative particles, such as one mole of calcium nuclei and one of calcium atoms.
<u>Answer:</u> The fugacity coefficient of a gaseous species is 1.25
<u>Explanation:</u>
Fugacity coefficient is defined as the ratio of fugacity and the partial pressure of the gas. It is expressed as 
Mathematically,

Partial pressure of the gas is expressed as:

Putting this expression is above equation, we get:

where,
= fugacity coefficient of the gas
= fugacity of the gas = 25 psia
= mole fraction of the gas = 0.4
P = total pressure = 50 psia
Putting values in above equation, we get:

Hence, the fugacity coefficient of a gaseous species is 1.25