B) energy is absorbed by the reaction
is right answer.
The answer is 3.5 × 10^-3
Answer: The current common definition of an acid and a base is based upon how the substance releases or attracts hydrogen ions (H+). Acids release H+ ions that can turn neutral molecules into positively charged ions, while bases can attract H+ ions from neutral molecules to produce negatively charged ions.
Explanation:
<u>Answer: </u>The correct statement is X is the effective nuclear charge, and it increases across a period.
<u>Explanation:</u>
We are given that:
X = number of protons − number of core electrons
Effective nuclear charge is defined as the actual nuclear charge (Z = number of protons) minus the screening effect caused by the electrons present between nucleus and valence electrons. These electrons are the core electrons.
The formula used for the calculation of effective nuclear charge given by Slater is:

where,
= effective nuclear charge
Z = atomic number or actual nuclear charge or number of protons
= Screening constant
The effective nuclear charge increases as we go from left to right in a period because nuclear charge increases with no effective increase in screening constant.
Hence, the correct answer is X is the effective nuclear charge, and it increases across a period.