NEET Chemistry: Periodic trends and properties of elements Practice Questions

Correct answer: D — Ionization Energy

Ionization Energy (IE) is the energy required to remove an electron from an atom. IE generally increases across a period and decreases down a group.

Correct answer: B — Decreases

As the number of protons in the nucleus increases, the effective nuclear charge increases, pulling the electron cloud closer, thus decreasing the atomic size.

Correct answer: C — Decreases consistently

As we move across a period (left to right), the number of protons increases, leading to a stronger effective nuclear charge, which pulls the electrons closer to the nucleus, thus decreasing the atomic radius.

Correct answer: B — Fluorine

Electronegativity is the tendency of an atom to attract a bonding pair of electrons. Fluorine (F) is the most electronegative element in the periodic table.

Correct answer: D — Ionization Energy

Ionization energy decreases down a group because the valence electrons are further from the nucleus and are shielded by more inner-shell electrons, making them easier to remove.

Correct answer: C — Rubidium

Atomic radius increases as we move down a group because the number of electron shells increases, leading to greater distance from the nucleus. Rubidium (Rb) is the heaviest alkali metal listed and has the largest size among these.

Correct answer: D — Chlorine

Electron gain enthalpy (or energy) is generally more negative (indicating a greater release of energy upon gaining an electron) for elements on the right side of the periodic table, especially halogens. Chlorine (Cl) typically has a larger gain than the alkali metals.

Correct answer: B — It increases continuously

As we move across a period, the effective nuclear charge increases, pulling the valence electrons more strongly. This makes it harder to remove an electron, thus the first ionization enthalpy (IE₁) generally increases across a period.

Correct answer: A — Increases

As we move down a group, the principal quantum number increases, adding new electron shells. This results in a significant increase in atomic size.

Correct answer: C — Decreases down a group

Electron gain enthalpy generally becomes less exothermic (less negative) as you move down a group because the valence shell is further from the nucleus, making the attraction less effective.

Correct answer: A — Li and Na

The difference in electronegativity is smallest between elements in the same group, particularly where the difference in nuclear charge is minimal. Mg and Al are adjacent metals with relatively similar properties compared to C/N or O/F differences.

Correct answer: B — Electronegativity decreases as atomic size increases

Electronegativity decreases down a group because the atomic size increases, meaning the nucleus has less effective pull on the valence electrons.

Correct answer: B — Neon (Ne)

Ionization enthalpy generally increases across a period because the effective nuclear charge increases, making it harder to remove an electron. Neon (Ne) has the highest ionization enthalpy in the second period.