How many shells are occupied in atoms of elements in period 4?

Explanation:

Since, Number of shells in an atom = number of period

Therefore, atoms of element will have 4 shells.

For example:

K (Potassium) is an element of 4th period whose atomic number is 19.

19 = 2, 8, 8, 1

it forms an anion that has a larger radius. anions have a negative charge and are larger than the original atom.

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.