General Science MCQ Practice

Explanation

• The sex of a newborn is determined by the father because sperm cells carry either X or Y chromosomes, while eggs from the mother carry only X.
• Chromosome concept: male = XY, female = XX. The child’s sex depends on which sperm chromosome fertilizes the egg.
• Numerical note: 50% of all sperm carry X, 50% carry Y, so 1:1 chance for each sex.
• Exam tip: Remember “Father contributes the determining chromosome.”

Why others are incorrect

• A, B, D: Mother’s side cannot determine the sex since all eggs have X; father’s sperm decides between X or Y.

Correct option: B

• 1, 2 and 4 are correct.
• Why: A barometer measures atmospheric pressure. Changes in pressure help estimate altitude (via hydrostatic relation: dP ≈ -ρg dh) and are used in weather forecasting (pressure trends indicate weather systems).
• Why not 3: It does not measure the density of liquids; a hydrometer or pycnometer is used for density.
• Exam tip: If a question asks about barometer functions, focus on pressure measurement first, then applications that rely on pressure trends.

Correct option: B - Radio waves

• Reason: Radar uses radio waves to detect aircraft by sending a radio pulse and measuring its reflection (echo) from objects.
• Key concept: Electromagnetic waves in the radio frequency range travel long distances and can reflect off metal objects like planes.
• Simple formula: Range ~ (speed of light × time delay)/2; time delay between transmitted and received pulse gives distance.
• Exam tip: If a question mentions detection of distant or fast-moving objects, think radio waves (radar).
• Why others are incorrect:
  • Sound waves: attenuate in air and require detectors near the object; not used for long-range detection.
  • Ultrasonic waves: high frequency, short range.
  • Infrared: limited range and weather sensitivity; not suitable for radar surveillance.

Answer: C

• Correct reason: LASER stands for Light Amplification by Stimulated Emission of Radiation. It uses stimulated emission to amplify light, producing coherent, intense beams.
• Key concept: Stimulated emission; photons trigger more photons with same phase, direction, and frequency.
• Quick note on formula: Energy of a photon E = hν supports the idea of selecting a fixed frequency ν for amplification.
• Why others are wrong: A uses absorption, B and D use steady emission or absorption, not amplification or stimulated emission.
• Exam tip: Remember “Stimulated Emission” is the core mechanism behind LASER.

Correct option: A — Black

• Reason: Without an atmosphere, there is no Rayleigh or Mie scattering to color the sky. Sunlight travels straight, and space appears black except where you see the Sun.
• Key concept: Sky color arises from scattering of light by atmospheric particles; in their absence, no scattered blue light is seen.
• Formula/logic (brief): If scattering coefficient ≈ 0, sky radiance is dominated by direct solar radiation; no diffuse blue glow.
• Exam tip: Remember: color of sky depends on atmosphere; remove it and the sky turns black.
• Why others are incorrect: White/Blue/Green require scattering or pigment; none occur without atmosphere.

Answer: D. Iron

• Reason: Sound travels faster in solids than liquids/gases because their molecules are tightly packed and have high elasticity. In solids, v ≈ √(E/ρ) for longitudinal waves, where E is the elastic modulus and ρ is density. Iron has a high modulus, so v is large even at 0°C.
• Why others are slower: Water, ice, and especially air have much lower elastic rigidity per density, so sound speed is much less.
• Exam tip: Remember: in general, the order is solids > liquids > gases for sound speed; metals > other solids.

Correct answer: C — Total internal reflection of light

• Key concept: Light is guided in optical fibres by total internal reflection (TIR); when light in a higher‑index core hits the core–cladding interface at angles above the critical angle, it reflects back entirely.
• Reason: This keeps light trapped inside the core as it travels long distances with minimal loss.
• Formula/idea: Using Snell’s law n1>n2 and θ1 > θc where sin θc = n2/n1.
• Why others are wrong: Dispersion spreads colors, scattering causes loss, refraction changes direction but does not confine light in fibres.

Exam tip: Remember the critical angle concept and higher core index (n1) compared to cladding (n2).

Correct option: B

• Key concept: Alcohols contain carbon, hydrogen, and oxygen in the hydroxyl (–OH) group. For example, ethanol has formula C2H5OH.
• Why B is correct: It lists C, H, O exactly as in common alcohols.
• Why others are incorrect: A and C include nitrogen; D includes chlorine—these are not typical elements in simple alcohols.
• Exam tip: Remember the general formula pattern for simple alcohols: CxHyOH.

Question: Government of India set up BEE, an autonomous Government Agency under Ministry of Power. BEE stands for:

• Correct option: A Bureau of Energy Efficiency

Explanation: BEE promotes energy conservation and efficiency across sectors. Key concept: energy efficiency improves output per unit energy used. There is no formula required here; remember the acronym expansion. Why correct: Option A correctly expands BEE as Bureau of Energy Efficiency. Why others incorrect: - B: Bureau of Electrical and Electronics – not the acronym. - C: Bureau of Enhanced Energy – not used. - D: Bureau of Energy Emission – not the term. Exam tip: Memorize government agencies by acronym + full form to quickly answer similar questions.