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 not a correct statement about Bitumen?
[A] It’s a mixture of highly condensed polycyclic aromatic compounds
[B] Its is soluble in Carbon Disulphide
[C] SARA analysis is used to determine bitumen chemistry
[D] All of above are correct statements
Show Answer
Correct Answer: D [ All of above are correct statements ]
Notes:
Bitumen is a mixture of organic liquids that are highly viscous, black, sticky, soluble in carbon disulfide and composed of highly condensed polycyclic aromatic hydrocarbons.
2. “Atoms can neither be created nor destroyed.” This principle was given by __?
[A] Avogadro
[B] Dalton
[C] Rutherford
[D] Niels Bohr
Show Answer
Correct Answer: B [Dalton]
Notes:
The given principle is one of the postulates of the Dalton’s atomic theory given in 1803 by John Dalton. The postulates of Dalton’s atomic theory are as follows:
1. Elements consist of indivisible small particles (atoms).
2. All atoms of the same element are identical; different elements have different types of atom.
3. Atoms can neither be created nor destroyed.
4. ‘Compound elements’ (i.e. Compounds) are formed when atoms of different elements join in simple ratios to form ‘compound atoms’ (i.e. Molecules).
3. What is the electrical state of a molecule, considered the smallest part of matter retaining the properties of the original matter?
[A] Positive
[B] Negative
[C] Either positive or negative
[D] Neutral
Show Answer
Correct Answer: D [Neutral]
Notes:
A molecule represents the smallest portion of a substance that retains the characteristics of the substance. It’s electrically neutral because it’s made up of atoms that bond together, sharing or exchanging electrons to achieve stability. This process balances out the electrical charges of the protons and electrons, rendering the molecule as a whole electrically neutral.
4. The chemical oxygen demand COD test is commonly used to measure which of the following?
[A] amount of organic compounds in water
[B] amount of oxygen in water
[C] amount of oxygen in a chemical
[D] amount of oxygen used in a oxygenation process
Show Answer
Correct Answer: A [amount of organic compounds in water]
Notes:
chemical oxygen demand is a measure of water quality and is amount of organic pollutants found in surface water. Potassium permanganate has been used for many years to measure COD
5. The Potassium graphite and Calcium Graphite can be mostly used as which among the following?
[A] Moderators
[B] Semiconductors
[C] Superconductors
[D] Lubricants
Show Answer
Correct Answer: C [Superconductors]
Notes:
Potassium graphite and calcium graphite are primarily used as superconductors. Superconductors are materials that can conduct electricity without resistance when cooled below a certain temperature. Graphite, particularly when doped with potassium or calcium, exhibits enhanced superconducting properties. Notably, the discovery of high-temperature superconductors in the 1980s revolutionized the field, leading to applications in magnetic levitation and advanced electronic devices.
6. 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.
7. The largest component of Coal gas is__?
[A] Methane
[B] Hydrogen
[C] Carbon Dioxide
[D] Carbon Monoxide
Show Answer
Correct Answer: B [ Hydrogen]
Notes:
Typical composition of the Coal gas is as follows: •Hydrogen 50% •Methane 35% •Carbon monoxide 10% •Ethylene 5%
8. Which of the following chemicals is also known as lachrymatory agent or lachrymator?
[A] Mustard Gas
[B] Tear gas
[C] Diborane
[D] Chlorine gas
Show Answer
Correct Answer: B [ Tear gas]
Notes:
Tear gas is also known as CS Gas. It acts as a lachrymatory agent. Tear gas irritate the mucous membrane of the eyes, nose, mouth and lungs, and causes tearing, coughing, burning and difficult breathing.
9. Which among the following acids is generally used as a first hand test to judge whether a metal is Gold or not?
[A] Sulfuric Acid
[B] Nitric Acid
[C] Hydrochloric Acid
[D] Sulfurous Acid
Show Answer
Correct Answer: B [Nitric Acid]
Notes:
The funda is that when a small drop of a strong acid, such as nitric acid, is put onto the metal’s surface, most metals fizz or bubble, whilst precious metals (Gold or Platinum not silver) are unaffected.
10. What is an alloy of mercury with some other metal generally known as?
[A] Galinston
[B] Amalgam
[C] Megalium
[D] Yellow metal
Show Answer
Correct Answer: B [Amalgam]
Notes:
Amalgam is the general name given to an alloy of mercury with some other metal. It can be a solid, liquid or a soft paste depending on the composition of the constituents.
