I really need someone to explain how to find the average atomic mass. the gizmos was really confusing because they also had weighted mass.

Option C. 52.057

Explanation:

The following data were obtained from the question:

Isotope >> Mass number > Percentage

A (Cr-50) > 50 >>>>>>>>>> 4.3

B (Cr-52) > 52 >>>>>>>>>> 83.8

C (Cr-53) > 53 >>>>>>>>>> 9.5

D (Cr-54) > 54 >>>>>>>>>> 2.4

Average atomic mass =?

The average atomic mass of chromium, Cr can be obtained as follow:

Average atomic mass = [(Mass of A × A%) /100] + [(Mass of B × B%) /100] + [(Mass of C × C%) /100] + [(Mass of D × D%) /100]

Atomic mass of Cr = [50×4.3)/100] + [52×83.8)/100] + [53×9.5)/100] + [54×2.4)/100]

= 2.15 + 43.576 + 5.035 + 1.296

Atomic mass of Cr = 52.057

Therefore, the atomic mass of chromium, Cr is 52.057

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.