General Science MCQ Practice

• Reason: Rh factor is an antigen. A Rh+ person has the antigen, so their blood can cause an immune reaction in a Rh- recipient. Therefore Rh+ → Rh- is not safe.
• Key concept: Rh incompatibility; Rh- can donate to both Rh- and Rh+ (with proper matching), but Rh+ cannot donate to Rh-.
• Tip: Always check Rh and ABO compatibility before blood transfusion.
• Why others are correct: A: Rh+ to Rh+ works; B: Rh- to Rh- works; C: Rh- to Rh+ works.

• Why D is not a property of acids: Acids turn blue litmus to red, not red to blue. So statement D is false for acids.
• Key concept: Acids have pH < 7, sour taste, and are often corrosive; litmus test: acids → red, bases → blue.
• Formula/note: pH < 7 indicates acidity (pH = 7 is neutral).
• Exam tip: Memorize litmus test colors: acids=red, bases=blue.

• Key concept: Lysosomes contain hydrolytic enzymes that digest waste, worn-out organelles, and foreign material.
• Reason: They are called "suicidal bags" because when damaged or in autophagy, their enzymes leak and destroy the cell, leading to cell death.
• Other options:
• Peroxisomes break down fats and detoxify but are not disposal units.
• Glyoxisomes perform lipid metabolism in plants; not general disposal units.
• Mitochondria generate ATP; not mainly for digestion.

Exam tip: Remember lysosomes are the cell’s digestive and recycling centers.

• Electrons are negatively charged and are present in the orbits.

Reason: An atom has a dense nucleus (protons positively charged; neutrons neutral). Electrons, negatively charged, occupy surrounding regions called orbits or orbitals. The total mass mainly comes from the nucleus, not the orbits. The electric charge balance is q(electron) = -e.

• Why others are wrong:
• A: Protons are positively charged and in the nucleus.
• B: Electrons are not in the nucleus and are negative.
• D: Mass is concentrated in the nucleus, not distributed in orbits.

Exam tip: Remember negative charges orbit a positive nucleus.

• The SI unit of force is the Newton (N), which equals kg·m/s².
• Key concept: Force causes acceleration via F = m a.
• Why others are wrong:
  • Work = force × distance; unit J = kg·m²/s².
  • Power = work per time; unit W = kg·m²/s³.
  • Motion is not a physical quantity with that unit.

Exam tip: Remember Newton = kg·m/s².

• Correct answer: B. Ultrasonography
• Why: USG stands for ultrasonography, an imaging method using high-frequency sound waves to create body images.
• Key concept: Ultrasound uses non-ionizing waves; echoes from tissues form the image.
• Tip: In medical terms, -ography often means imaging/viewing; USG specifically indicates ultrasound imaging.
• Why other options are incorrect: A and C are unrelated medical terms; D is incorrect since B is correct.

• Explanation: In metric volume, 1 L = 10 dL = 1000 mL. So from largest to smallest: Litre > decilitre > millilitre.
• Key concept: Metric prefixes: L (litre) is the base unit for volume; dL = 0.1 L; mL = 0.001 L.
• Why others are wrong: A has “lite” misspelt; C starts with smaller unit (dL) before larger; D ends with smaller unit after mL.
• Exam tip: memorize 1 L = 1000 mL and 1 L = 10 dL for quick comparisons.

• Why: Oceans dissolve and store large amounts of carbon as dissolved inorganic carbon and carbonates. Henry’s law governs CO2 dissolution in water: CO2(aq) ∝ partial pressure of CO2. Over time, biology (concerted carbon pump) moves carbon to deep oceans.
• Compared to others: Grasslands, forests store carbon mainly in biomass and soils but in total contain less carbon than the ocean’s dissolved reservoir; agroecosystems are smaller and less carbon-dense; forests are strong but still far less than oceans’ long-term storage.
• Tip: Remember “ocean = largest carbon sink” among the options.