General Science — MCQ Practice Questions & Answers

Question 1

In the reaction between potassium permanganate and oxalic acid in acidic medium, what is the ratio of KMnO₄ to H₂C₂O₄ in the balanced equation?

Accepted Answer

Correct answer: B. 2:5 — The balanced equation for this redox reaction in acidic medium is: 2KMnO₄ + 5H₂C₂O₄ + 3H₂SO₄ → K₂SO₄ + 2MnSO₄ + 10CO₂ + 8H₂O. Potassium permanganate acts as an oxidizing agent (Mn⁷⁺ → Mn²⁺), while oxalic acid is oxidized (C²⁺ → C⁴⁺), giving the 2:5 molar ratio.

Answer

A. 1:2

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C. 3:5

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D. 5:2

Question 2

What is the hybridization state of the central carbon atom in the carbonate ion (CO₃²⁻)?

Accepted Answer

Correct answer: B. sp² — In the carbonate ion CO₃²⁻, the central carbon atom forms three sigma bonds with oxygen atoms and is involved in resonance structures with delocalized pi electrons. This trigonal planar geometry requires sp² hybridization, with three hybrid orbitals arranged at 120° angles and one unhybridized p orbital for pi bonding.

Answer

A. sp

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C. sp³

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D. sp³d

Question 3

The escape velocity from the surface of a planet depends on which two fundamental properties of that planet?

Accepted Answer

Correct answer: B. Mass and radius — Escape velocity is mathematically derived as v = √(2GM/R), where G is gravitational constant, M is the planet's mass, and R is its radius. These two properties directly determine the gravitational field strength at the planet's surface, which defines the minimum velocity needed to escape gravitational attraction.

Answer

A. Radius and temperature

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C. Density and temperature

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D. Atmospheric pressure and mass

Question 4

What is the primary reason why Venus experiences a runaway greenhouse effect compared to Earth, despite being only slightly closer to the Sun?

Accepted Answer

Correct answer: A. Venus has a much thicker atmosphere composed primarily of carbon dioxide with clouds of sulfuric acid — Venus's dense atmosphere (90 times denser than Earth's) is composed of 96.5% carbon dioxide with clouds of concentrated sulfuric acid, creating an extreme greenhouse effect with surface temperatures around 465°C. This massive atmospheric composition traps far more infrared radiation than Earth's atmosphere, making it the primary cause of Venus's extreme greenhouse conditions rather than its orbital position alone.

Answer

B. Venus rotates much faster than Earth, trapping more heat

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C. Venus lacks a magnetic field to protect it from solar radiation

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D. Venus is larger in size and therefore has greater gravitational compression

Question 5

The James Webb Space Telescope observes primarily in which wavelength region of the electromagnetic spectrum, and what is the key advantage of this choice?

Accepted Answer

Correct answer: C. Infrared; allows observation through cosmic dust and enables viewing of early universe objects — The James Webb Space Telescope operates primarily in infrared wavelengths (0.6-28 micrometers), which penetrates dust clouds that block visible light, allowing it to observe star-forming regions, protoplanetary disks, and extremely distant galaxies from the early universe. Infrared observations also reveal objects too cool or distant to be seen in visible light, making it superior for studying the universe's earliest structures and most distant objects.

Answer

A. Ultraviolet; better for observing hot, young stars

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B. Visible light; provides clearest images of the universe

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D. Microwave; measures the cosmic microwave background radiation directly

Question 6

Speed of sound in air?

Accepted Answer

Correct answer: B. 343 m/s — ~343 m/s at 20°C.

Answer

A. 300 m/s

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C. 400 m/s

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D. 250 m/s

Question 7

Universal blood donor group?

Accepted Answer

Correct answer: D. O- — O- has no antigens, universal donor.

Answer

A. A+

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B. B+

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C. AB+

Question 8

In C4 plants, the first stable compound formed during carbon fixation is:

Accepted Answer

Correct answer: B. Oxaloacetate — In C4 photosynthesis, CO2 combines with PEP (3-carbon) to form oxaloacetate (4-carbon compound) via the enzyme PEP carboxylase.

Answer

A. 3-Phosphoglycerate

Answer

C. Ribulose-1,5-bisphosphate

Answer

D. Glucose

General Science - MCQ Practice Questions