A solution was prepared by dissolving 195.0 g of KCl in 215 g of water. Calculate the mole fraction of KCl. (The formula weight of KCl is 74.6 g/mol. The formula weight of water is 18.0 g/mol.)

Approximately .

Explanation:

The mole fraction of a compound in a solution is:

.

In this question, the mole fraction of in this solution would be:

.

This solution consist of only and water (i.e., .) Hence:

.

From the question:

Apply the formula to find the number of moles of and in this solution.

.

.

The molar fraction of in this solution would be:

.

(Rounded to three significant figures.)

answer; 4 electrons;

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.