General Science MCQ Practice

• Aryabhatta is renowned for contributions to mathematics and astronomy, not as a doctor, poet, or physicist.
• Key concept: early use of zero/place value and mathematical approximations, e.g., pi ≈ 22/7.
• Rule/logic: He laid foundations of Indian mathematics and calculated celestial motions using mathematical methods.
• Exam tip: Remember him as a mathematician who also studied astronomy; don’t confuse with later scientists.
• Other options: Doctor, Poet, Physicist are incorrect as his fame is primarily in math and astronomy.

• Reason: Nickel exposure commonly causes allergic contact dermatitis (a type IV hypersensitivity). It leads to skin itch, redness, and rashes at the contact site.
• Key concept: Nickel allergy is a classic example of cell-mediated (T-cell) immune reaction to a metal.
• Quick note on others: Itai-Itai is due to cadmium poisoning; learning disabilities and asthma are not specific to nickel exposure.
• Exam tip: Remember metals often cause contact dermatitis rather than systemic diseases.

• Correct answer: B (37 ?) refers to 37°C, the typical normal core body temperature for a healthy adult.
• Key concept: Normal human temperature is measured in Celsius on the standard scale; ~36.5–37.5°C is considered normal.
• Reasoning: 37°C ≈ 98.6°F; 98.4 is a Fahrenheit value and not the commonly stated Celsius normal.
• Exam tip: If given values in °C, choose around 37; if in °F, around 98–99.
• Why others are incorrect: 14.5°C and 25°C are far below human core temperature; 98.4 (if interpreted as °F) is not in °C terms.

• Why correct: A single CFC molecule liberates chlorine atoms in the stratosphere, which catalytically destroy many ozone (O3) molecules. The typical estimate is about 100,000 O3 molecules per Cl atom, i.e., per CFC molecule. Net reaction: Cl + O3 → ClO + O2; ClO + O → Cl + O2; overall O3 → 2 O2.

• Reason: The Earth’s average distance from the Sun is about 1 astronomical unit (AU) ≈ 149.6 million km, often approximated as 150 million km.
• Key concept: Orbital distance varies seasonally due to elliptical orbit; the average distance defines 1 AU.
• Formula/numerical note: 1 AU ≈ 1.496 × 10^8 km.

• Reason: Prithvi was the first missile developed by India under the Integrated Guided Missile Development Programme (IGMDP) in the 1980s, marking India’s entry into indigenous ballistic missile development.
• Key concept: It is a short-range surface-to-surface ballistic missile (SRBM). Early Prithvi used liquid propellant; later variants improved guidance and range.
• Why others are incorrect: A) Agni—later long-range ballistic missile; B) Aakash—SRBM with different guidance; C) Trishul—short-range air defense/strategic project, not the first.

Exam tip: Remember the sequence—Prithvi first, then Agni.

• Correct answer: C — Faraday is associated with electromagnetism and electrochemistry, not diffusion of gases.
• Key concept: scientific contributions are tied to specific areas (Faraday = electricity/magnetism; diffusion of gases linked to Graham’s law, kinetic theory).
• Why others are correct:
  • (A) Roentgen : X-ray — correct; Wilhelm Röntgen discovered X-rays.
  • (B) Newton : Law of gravitation — correct; Newton formulated the law of gravitation.
  • (D) Pasteur : Bacteriology — correct; Pasteur advanced germ theory and bacteriology.
• Exam tip: match scientists to their landmark field, not a related concept to avoid mistakes.

• Correct answer: A. Decibel
• The unit of sound intensity is the decibel (dB), representing a logarithmic scale of loudness.
• Concept: Sound pressure level (SPL) or intensity I is measured as dB = 10 log10(I/I0) (or using reference pressure p0), which compresses a huge range of values into a manageable scale.
• Exam tip: Remember dB is a relative unit, not an absolute amplitude unit.
• Why others are incorrect: Coulomb measures electric charge, Henry measures inductance, Hertz measures frequency.

• Riboflavin is the chemical name for Vitamin B2.
• Key concept: Vitamin B2 forms FAD and FMN, coenzymes in redox reactions (electron transfer).
• Other options: Haemoglobin is a protein carrying oxygen; Dextrose is glucose; Thiamine is Vitamin B1.
• Exam tip: Memorize common vitamin-letter-name pairs (A for retinol, B2 for riboflavin).