Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. Which of the following is the most active chemically?
[A] Chlorine
[B] Flourine
[C] Lithium
[D] Iodine
Show Answer
Correct Answer: B [Flourine]
Notes:
Fluorine is most active because it has the highest electronegativity.
2. When Ozone is heated its volume will…. ?
[A] increases
[B] decreases
[C] remains unchanged
[D] First Increase, then decrease
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Correct Answer: C [remains unchanged]
Notes:
When Ozone is heated its volume will remain unchanged. It might change volume to an extent but not to a great extent.
3. Galvanizing is a metallurgical process that is used to coat steel or iron with which of the following?
[A] Zinc
[B] Lead
[C] Chromium
[D] Copper
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Correct Answer: A [Zinc]
Notes:
Galvanisation is a method of protecting steel and iron from rusting by coating them with a thin layer of zinc
4. Which among the following is the lowest atomic number element without any stable isotopes?
[A] Technetium
[B] Molybdenum
[C] Ruthenium
[D] Niobium
Show Answer
Correct Answer: A [Technetium]
Notes:
The correct answer is Technetium. It has the atomic number 43 and is the lowest atomic number element without any stable isotopes. All of its isotopes are radioactive, with Technetium-98 being the most stable, having a half-life of about 4.2 million years. Technetium was first artificially produced in 1937 by Carlo Perrier and Emilio Segrè, making it the first element to be artificially created.
5. Which among the following gas has lowest auto-ignition temperature?
[A] Methane
[B] Hydrogen
[C] Ethylene
[D] Carbon Di Sulphide
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Correct Answer: D [Carbon Di Sulphide]
Notes:
The auto-ignition temperature of a liquid, gas or vapor is the temperature at which the substance will ignite without any external heat source. Here is the temperature of some gases:
Methane -580 °C
Hydrogen -560 °C
Propane -493 °C
Ethylene -425 °C
Acetylene -305 °C
Naphtha -290 °C
Carbon disulfide -102 °C
6. Which among the following minerals is also known as Horn Silver?
[A] Silver Iodide
[B] Silver Chroride
[C] Zinc Phosphate
[D] Silver Sulphide
Show Answer
Correct Answer: B [Silver Chroride]
Notes:
Chlorargyrite is the mineral form of silver chloride (AgCl). It is also known as cerargyrite and, when weathered by desert air, as horn silver. Silver chloride is formed by the disappearance of the initial silver oxide layer.
7. How does vulcanization make natural rubber more durable?
[A] The long polymer chains are shortened
[B] The rubber loses water and sticky substances
[C] The short polymer chains are lengthened
[D] Cross links form between the polymer chains
Show Answer
Correct Answer: D [Cross links form between the polymer chains]
Notes:
Vulcanization introduces sulfur cross-links between poly-isoprene chains in natural rubber, restricting movement, which increases stiffness, elasticity, and durability. This chemical modification prevents rubber from becoming sticky or brittle, significantly improving its mechanical properties for industrial and commercial use.
8. Which of these is NOT an allotropic form of carbon?
[A] Diamond
[B] Graphite
[C] Fullerene
[D] None of the above
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Correct Answer: D [None of the above]
Notes:
Carbon exhibits many allotropic forms; both crystalline as well as amorphous. Diamond and graphite are two well-known crystalline forms of carbon. In 1985, third form of carbon known as fullerenes was discovered.
9. Which of these methods is suitable to obtain the coloured component from black ink?
[A] Evaporation
[B] Sublimation
[C] Crystallisation
[D] All of the above
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Correct Answer: A [Evaporation]
Notes:
The dye from water can be separated by the method of evaporation. Evaporation is used to separate the volatile component (solvent) from its non-volatile solute.
10. Which of the following is incorrect statement about various ores?
[A] Borax is an ore of Sodium
[B] Dolomite is an ore of Aluminium
[C] The chemical formula of Magnetite is Fe3O4
[D] Flourspar is an ore of Potassium
Show Answer
Correct Answer: D [Flourspar is an ore of Potassium]
Notes:
Fluorite or Fluorspar is an ore of Calcium. It is a mineral composed of calcium fluoride. It belongs to the family of halide minerals.
