MCQ Practice

General Science (Everyday Science) MCQs

Which compound has the largest bond angle around the central atom?

A. NH₃
B. H₂O
C. CH₄
D. BF₃

Explanation:
Trigonal planar BF₃ has 120°, larger than tetrahedral-derived or bent geometries.

Which orbital overlap forms a (\pi) bond?

A. End-to-end overlap along internuclear axis
B. Side-by-side overlap of parallel p orbitals
C. Overlap of s with s only
D. Overlap of hybrid orbitals only

Explanation:
(\pi) bonds arise from lateral overlap above and below the bond axis.

Which statement best describes a catalyst?

A. It changes (\Delta G) of reaction
B. It changes equilibrium constant
C. It lowers activation energy for forward and reverse reactions
D. It is consumed stoichiometrically

Explanation:
A catalyst accelerates both directions equally without shifting equilibrium.

For a first-order reaction, the half-life is:

A. Dependent on initial concentration
B. Independent of initial concentration
C. Zero-order only
D. Proportional to activation energy only

Explanation:
First-order half-life is constant for a given rate constant.

Which law predicts the effect of concentration on equilibrium position?

A. Hess’s law
B. Le Châtelier’s principle
C. Boyle’s law
D. Faraday’s law

Explanation:
Equilibrium shifts to oppose an imposed concentration change.

The oxidation state of chromium in (Cr_2O_7^{2-}) is:

A. +3
B. +4
C. +6
D. +7

Explanation:
Letting Cr be (x), (2x+7(-2)=-2) gives (x=+6).

Which species is amphoteric in Brønsted-Lowry theory?

A. (NH_4^+)
B. (OH^-)
C. (HCO_3^-)
D. (Cl^-)

Explanation:
Bicarbonate can both donate and accept a proton.

The conjugate base of (H_2PO_4^-) is:

A. (H_3PO_4)
B. (HPO_4^{2-})
C. (PO_4^{3-})
D. (H_2PO_3^-)

Explanation:
A conjugate base differs by loss of one proton.

Which intermolecular force is dominant between nonpolar noble gas atoms?

A. Ion-dipole
B. Hydrogen bonding
C. Dipole-dipole
D. London dispersion

Explanation:
Instantaneous induced dipoles dominate interactions between nonpolar atoms.

Which molecule is expected to be polar?

A. CO₂
B. BF₃
C. CH₄
D. SO₂

Explanation:
SO₂ is bent, so its bond dipoles do not cancel.