What caused the shielding effect to remain constant across a period

When moving from left to the right of a period, the number of electrons increases and the strength of shielding increases. As you move across period the number of shells remain same, the shielding effect will also remain constant.

Explanation:

the maximum mass of nh3 is nh3 in grams

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.