General Science — MCQ Practice Questions & Answers

Question 1

Which of the following compounds exhibits both ionic and covalent bonding characteristics and is commonly used in coordination chemistry?

Accepted Answer

Correct answer: B. Potassium hexacyanoferrate(III) — Potassium hexacyanoferrate(III) contains both ionic bonds (between K⁺ and the [Fe(CN)₆]³⁻ complex) and covalent bonds (between Fe and CN ligands, and within the CN groups). This complex salt is extensively used in coordination chemistry and analytical procedures like the Prussian blue test.

Answer

A. Sodium chloride

Answer

C. Carbon dioxide

Answer

D. Calcium oxide

Question 2

Which of the following substances will have the lowest lattice enthalpy among ionic compounds?

Accepted Answer

Correct answer: C. CsI — Lattice enthalpy depends inversely on ionic radius and directly on ionic charge. CsI has the lowest lattice enthalpy (~604 kJ/mol) because both Cs⁺ and I⁻ are large ions with 1+ and 1- charges respectively. In contrast, MgO has very high lattice enthalpy due to small, highly charged ions (Mg²⁺ and O²⁻), while NaCl and CaF₂ have intermediate values.

Answer

A. NaCl

Answer

B. MgO

Answer

D. CaF₂

Question 3

Which of the following statements about the Oort Cloud is incorrect?

Accepted Answer

Correct answer: D. It has been directly observed through telescopes and contains approximately 1 trillion objects — The Oort Cloud remains theoretical and has never been directly observed; we infer its existence from comet trajectories and orbital studies. While estimates suggest it contains billions to trillions of icy bodies, these objects are too distant and too small to be directly observed with current technology, making option D the incorrect statement among the given choices.

Answer

A. It is a theoretical spherical shell of icy bodies surrounding our solar system

Answer

B. It extends approximately 100,000 to 200,000 AU from the Sun

Answer

C. It is the primary source of long-period comets

Question 4

The pulling force that moves water upward in xylem vessels is primarily due to:

Accepted Answer

Correct answer: C. Transpirational pull (tension) in xylem — Cohesion-tension theory explains that water is pulled upward due to transpirational pull creating negative pressure in xylem.

Answer

A. Root pressure alone

Answer

B. Capillary action alone

Answer

D. Gravitational force

Question 5

In the nitrogen cycle, the conversion of atmospheric N2 into ammonia is carried out by:

Accepted Answer

Correct answer: B. Rhizobium — Rhizobium bacteria in root nodules of legumes fix atmospheric nitrogen into ammonia through nitrogenase enzyme.

Answer

A. Nitrosomonas

Answer

C. Nitrobacter

Answer

D. Thiobacillus

Question 6

When a plant wilts despite adequate soil moisture, this condition is called:

Accepted Answer

Correct answer: C. Physiological wilting — Physiological wilting occurs when transpiration rate exceeds water absorption rate, though soil moisture is sufficient.

Answer

A. Permanent wilting point

Answer

B. Incipient wilting

Answer

D. Hydration stress

Question 7

The double fertilization process in angiosperms results in the formation of:

Accepted Answer

Correct answer: B. Endosperm and embryo — Double fertilization: one sperm fuses with egg nucleus (embryo), other fuses with polar nuclei (endosperm - 3n).

Answer

A. Seed coat and cotyledon

Answer

C. Fruit and seed

Answer

D. Ovule and nucellus

Question 8

Which of the following shows the highest photosynthetic efficiency?

Accepted Answer

Correct answer: B. C4 plants in hot, dry climate — C4 plants have higher photosynthetic efficiency (~60%) compared to C3 plants (~30%) because they concentrate CO2 around RuBisCO, reducing photorespiration. This adaptation makes them suited for hot climates - important agricultural knowledge.

Answer

A. C3 plants in cool, moist climate

Answer

C. CAM plants during day

Answer

D. All show equal efficiency

General Science - MCQ Practice Questions