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General Science MCQ Practice
Practice General Science questions with instant scoring, correct answer highlighting, detailed solutions and first-click AI explanation caching for missing explanations.
📚 Questions: 553
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Q. 959
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Which of the following will not cause any atmospheric pollution ?
Explanation
- Correct answer: A — Hydrogen burns cleanly to form water: 2H2 + O2 → 2H2O. It does not produce conventional atmospheric pollutants.
- Other options cause pollution: SO2 from burning sulfur; CO from incomplete combustion; CO2 is a greenhouse gas and contributes to climate change.
- Key concept: Clean fuels produce minimal or no harmful gases; pollutants arise from oxidized or incomplete combustion products.
Q. 958
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Heavy water is :
Correct option: C Why: Heavy water is deuterium oxide (D2O). It uses deuterium, an isotope of hydrogen with an extra neutron, making the molecule twice as heavy as ordinary H2O. Key concept: Isotopes change atomic mass but not chemical identity; replacing H with D increases molecular weight. Other options: Tip: Remember “D” stands for deuterium in heavy water.
- A. Ice – not all heavy; ordinary water or ice.
- B. Water at 4°C – standard water, not heavy.
- D. Sugar solution – irrelevant to isotope composition.
Q. 957
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Which of the following diseases is caused by virus ?
- Correct option: D — Smallpox
- Reason: Smallpox is caused by the variola virus, a virus. The other diseases are caused by bacteria: cholera (Vibrio cholerae), typhoid (Salmonella typhi), and tuberculosis (Mycobacterium tuberculosis).
- Key concept: viruses are acellular pathogens that replicate only inside host cells.
- Tip: Remember viral diseases often end with “-pox” for historic examples; vaccines target viruses.
Q. 956
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Which of the following elements is essential for the transmission of nerve impulses in nerve fibers of human body ?
Correct option: C - Sodium
- Why: Nerve impulses travel as action potentials. Opening Na+ channels allows Na+ influx, depolarizing the membrane and transmitting the signal along the fiber.
- Key concept: Resting potential and depolarization trigger the action potential; the Na+/K+ pump restores resting state.
- Formula/logic: Membrane potential changes when Na+ moves in; threshold reached → rapid depolarization.
- Exam tip: Remember “Sodium for signal” to link Na+ with nerve impulse transmission.
- Why others are incorrect: Calcium mainly triggers neurotransmitter release at synapses; Iron and Zinc are not primary carriers of nerve impulse along axons.
Q. 955
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All enzymes are actually
Correct answer: A — Protein
- Why: Enzymes are biological catalysts; most are proteins formed from amino acids, with specific active sites that lower activation energy to speed reactions.
- Key concept: Enzyme activity depends on protein structure (shape, folding) and environment (pH, temperature).
- Exception (brief): A few RNA molecules act as enzymes (ribozymes), but in standard MCQ contexts enzymes are classically proteins.
- Tip: If a question asks “All enzymes,” remember the common teaching that proteins are the typical enzymes; note the ribozyme exception only in advanced topics.
- Incorrect options: Carbohydrates, fats, and steroids are not enzyme types; they are other biomolecules.
Q. 954
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The largest gland of human body is :
- Correct option: D. Liver
- The liver is the largest gland in the human body by weight (about 1.5 kg in adults) and performs many essential functions, including bile production and metabolism.
- Key concept: size by weight does not negate a gland’s role; the liver is an organ with endocrine and exocrine functions.
- Why others are incorrect: thyroid is a small endocrine gland; kidneys are paired organs, not a single largest gland; pancreas is about ~100–150 g—much smaller.
- Exam tip: remember “liver” is the largest gland; this helps distinguish from other common organs.
Q. 953
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Growth hormone is produced by :
Explanation
- Correct answer: B Growth hormone (GH) is secreted by the anterior pituitary gland. It regulates growth and metabolism in the body.
- Key concept: Endocrine signaling from the pituitary controls many hormones; GH acts on bones and muscles mainly.
- Why others are incorrect: A. Bones—they respond to GH, not produce it. C. Thyroid gland—produces thyroid hormones, not GH. D. Adrenal gland—produces cortisol, adrenaline, etc.
- Exam tip: Remember “pituitary = master gland” for several hormones.
Q. 952
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Bronchitis is a disease of :
Explanation:
- Correct answer: D — Bronchitis is an inflammation of the bronchi, i.e., the respiratory tract.
- Key concept: It affects the air passages of the respiratory system, causing coughing and mucus.
- Why others are incorrect: A (Blood), B (Liver), C (Intestine) are not parts of the respiratory system and are not involved in bronchitis.
- Tip: Remember “bronchi = air tubes in the respiratory tract.”
Q. 951
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Which of the following adds/add carbon dioxide to the carbon cycle on the planet earth ? 1. Volcanic action
2. Respiration
3. Photosynthesis
4. Decay of organic matter (Select correct answer)
Preparing explanation...
Q. 950
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Which of the following is an operating system ?
Correct answer: B. Windows XP
- Why it's correct: Windows XP is an operating system that manages hardware, runs applications, and handles resources.
- Key concept: An OS coordinates all computer components and user programs.
- Why others are incorrect:
- A. Floppy — a storage medium, not an OS.
- C. Oracle — database software, not an OS.
- D. ROM — hardware memory, not an OS.
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