NEET (UG)

Practice Test 1 — Classification of Elements & Periodicity in Properties

12 questions • 18 minutes • auto-graded with full solutions

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Section A — MCQ (Single Correct & Statement-based)

Question 1

The modern periodic law is based on atomic:

Solution: Atomic number (Moseley).

Question 2

An element with configuration $[\text{Ne}]\,3s^2\,3p^5$ belongs to group:

Solution: $10 + (2+5) = 17$ (a halogen).

Question 3

Which has the smallest size among these isoelectronic species?

Solution: $\text{Mg}^{2+}$ has the most protons.

Question 4

Consider the statements: (I) Atomic radius decreases across a period. (II) Atomic radius increases down a group. Which are correct?

Solution: Both trends are correct.

Question 5

The first ionisation enthalpy is higher for:

Solution: Half-filled $2p^3$ makes $\Delta_i H(\text{N}) > \Delta_i H(\text{O})$.

Question 6

The element with the most negative electron gain enthalpy is:

Solution: Cl exceeds F due to F's compact shell.

Question 7

Down a group, metallic character generally:

Solution: Lower ionisation enthalpy down a group increases metallic character.

Question 8

The d-block elements are also called:

Solution: d-block = transition elements.

Section B — Assertion & Reason

Question 9

A: The ionisation enthalpy of beryllium is greater than that of boron.
R: Beryllium has a stable, completely filled $2s^2$ configuration.

Solution: The stable $2s^2$ makes Be harder to ionise than B — R explains A.

Question 10

A: A cation is smaller than its parent atom.
R: Removal of electrons increases the effective nuclear pull on the remaining electrons.

Solution: Fewer electrons under the same nucleus shrink the ion — R explains A.

Question 11

A: Fluorine has a more negative electron gain enthalpy than chlorine.
R: Fluorine is the most electronegative element.

Solution: Chlorine's EGE is more negative than fluorine's, so A is false; R (F most electronegative) is true.

Question 12

A: Atomic number, not atomic mass, is the basis of the modern periodic table.
R: Moseley showed that element properties depend on the number of protons.

Solution: Moseley's finding is exactly why atomic number is the basis — R explains A.