NEET 2025 MCQ with Answer Explanation : Trends in Periodic Properties.

Here below some basic MCQ’s about “Trends in periodic properties” which is explained in details. Let’s check one by one which is given below.

1. Which of the following elements has the highest first ionization energy?
   a) Sodium (Na)
   b) Magnesium (Mg)
   c) Aluminum (Al)
   d) Phosphorus (P)

Answer: d) Phosphorus (P)

Explanation: Ionization energy generally increases across a period due to the increasing effective nuclear charge, which makes it harder to remove an electron. Phosphorus lies farthest to the right in this group, hence has a higher ionization energy than Na, Mg, and Al. Also, due to half-filled p-orbital stability, phosphorus has a higher ionization energy than aluminum.

2. Which of the following elements has the largest atomic radius?
   a) Carbon (C)
   b) Nitrogen (N)
   c) Oxygen (O)
   d) Fluorine (F)

Answer: a) Carbon (C)

Explanation: Atomic radius decreases across a period from left to right due to increasing effective nuclear charge. Carbon, being the leftmost element in this group, has the largest atomic radius among these elements.

3. In which period of the periodic table is the element with the electronic configuration [Ar] 3d¹⁰ 4s² 4p⁵ located?
   a) Period 3
   b) Period 4
   c) Period 5
   d) Period 6

Answer: b) Period 4

Explanation: The element has the outer electronic configuration 4s² 4p⁵, indicating that the last electron enters the 4th energy level. This places the element in period 4. The element is bromine (Br).

4. Which of the following oxides is most acidic?
   a) Na₂O
   b) Al₂O₃
   c) SiO₂
   d) SO₃

Answer: d) SO₃

Explanation: Acidity of oxides increases across a period and decreases down a group. Non-metal oxides (like SO₃) tend to be more acidic, while metal oxides (like Na₂O) are basic. SO₃, being a non-metal oxide, is highly acidic.

5. Which property decreases down the group in alkali metals?
   a) Atomic radius
   b) Ionization energy
   c) Metallic character
   d) Electronegativity

Answer: d) Electronegativity

Explanation: As we move down the group in alkali metals, atomic size increases, leading to decreased attraction for electrons, hence decreasing electronegativity. Ionization energy also decreases, but metallic character increases down the group.

6. Which of the following elements has the smallest electron affinity?
   a) Fluorine (F)
   b) Chlorine (Cl)
   c) Oxygen (O)
   d) Sulfur (S)

Answer: a) Fluorine (F)

Explanation: While fluorine is expected to have high electron affinity, it is actually lower than chlorine’s. This is due to the small size of fluorine, which causes electron-electron repulsion when an extra electron is added, lowering its electron affinity.

7. The ability of an atom in a molecule to attract shared electrons towards itself is called:
   a) Ionization energy
   b) Electron affinity
   c) Electronegativity
   d) Metallic character

Answer: c) Electronegativity

Explanation: Electronegativity is a measure of an atom’s ability to attract bonding electrons in a molecule. It differs from ionization energy and electron affinity, which refer to individual atoms in different contexts.

8. Which of the following elements shows diagonal relationship with Lithium?
   a) Sodium
   b) Magnesium
   c) Potassium
   d) Beryllium

Answer: d) Beryllium

Explanation: Lithium and beryllium show a diagonal relationship due to similarities in their properties such as atomic and ionic sizes, electronegativity, and polarization power, despite being in different groups.

9. Which of the following elements has the highest electronegativity?
   a) Oxygen (O)
   b) Nitrogen (N)
   c) Fluorine (F)
   d) Chlorine (Cl)

Answer: c) Fluorine (F)

Explanation: Fluorine is the most electronegative element in the periodic table. It has a strong ability to attract electrons towards itself in a chemical bond due to its small size and high effective nuclear charge.

10. Which of the following statements is incorrect about the trends in the periodic table?
    a) Electronegativity decreases down a group.
    b) Atomic radius increases down a group.
    c) Ionization energy increases across a period.
    d) Metallic character increases across a period.

Answer: d) Metallic character increases across a period

Explanation: Metallic character decreases across a period from left to right due to increasing ionization energy and electronegativity, making elements less likely to lose electrons and form positive ions.