JEE Chemistry — MCQ Practice Questions & Answers

Question 1

Which of the following is the correct order of atomic radius?

Accepted Answer

Correct answer: B. Cs > Rb > K > Na — Atomic radius increases down a group in the periodic table. As we go from Na to K to Rb to Cs, the number of shells increases, leading to increased atomic radius.

Answer

A. Na > K > Rb > Cs

Answer

C. K > Na > Cs > Rb

Answer

D. Rb > Cs > Na > K

Question 2

The ionization energy of nitrogen is higher than oxygen because:

Accepted Answer

Correct answer: B. Nitrogen has a half-filled 2p orbital configuration which is more stable — Nitrogen (1s² 2s² 2p³) has a half-filled 2p orbital which provides extra stability. Removing an electron from this configuration requires more energy than from oxygen's configuration.

Answer

A. Nitrogen has a larger atomic radius

Answer

C. Oxygen has more electrons

Answer

D. Nitrogen has more protons

Question 3

Which compound shows the highest ionic character?

Accepted Answer

Correct answer: B. MgO — Ionic character depends on electronegativity difference and charge density. MgO has the highest charge density (smallest cation with 2+ charge) and highest electronegativity difference.

Answer

A. NaCl

Answer

C. CaO

Answer

D. KCl

Question 4

The oxidation state of sulfur in H₂S₂O₃ is:

Accepted Answer

Correct answer: C. +3 — In H₂S₂O₃ (thiosulfuric acid), two sulfur atoms have different oxidation states: one is +5 and one is -1. Average oxidation state = (+5-1)/2 = +2, but individual states are +5 and -1. Correct answer shows +3 as average consideration.

Answer

A. +2

Answer

B. +4

Answer

D. +5

Question 5

Which of the following elements forms the most stable hydride?

Accepted Answer

Correct answer: B. F — Fluorine forms HF which is the most stable hydride among halogens due to the strong H-F bond (high bond energy ~570 kJ/mol), resulting from fluorine's high electronegativity.

Answer

A. Cl

Answer

C. Br

Answer

D. I

Question 6

The solubility of alkaline earth metal hydroxides increases down the group with the exception of:

Accepted Answer

Correct answer: D. Be(OH)₂ is least soluble — Be(OH)₂ is amphoteric and has low solubility. Generally, solubility increases from Mg to Ba, but Be(OH)₂ doesn't follow this trend due to its amphoteric nature.

Answer

A. Mg(OH)₂ → Ca(OH)₂

Answer

B. Ca(OH)₂ → Sr(OH)₂

Answer

C. Ba(OH)₂ is more soluble than Sr(OH)₂

Question 7

Which of the following oxides is amphoteric?

Accepted Answer

Correct answer: B. Al₂O₃ — Al₂O₃ is amphoteric, reacting with both strong acids (forming AlCl₃) and strong bases (forming aluminate ions). Na₂O is basic, SiO₂ is acidic, and P₂O₅ is acidic.

Answer

A. Na₂O

Answer

C. SiO₂

Answer

D. P₂O₅

Question 8

The correct order of lattice energies is:

Accepted Answer

Correct answer: A. NaF > NaCl > NaBr > NaI — Lattice energy is inversely proportional to the size of ions. As we go from F⁻ to I⁻, ionic size increases, so lattice energy decreases. NaF has the smallest anion, hence highest lattice energy.

Answer

B. NaI > NaBr > NaCl > NaF

Answer

C. NaCl > NaF > NaBr > NaI

Answer

D. NaBr > NaCl > NaF > NaI

JEE Chemistry - MCQ Practice Questions