Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. A high-refractive-index polymer (HRIP) is a polymer that has a refractive index greater than _?
[A] .50
[B] 1.0
[C] 1.20
[D] 1.50
Show Answer
Correct Answer: D [1.50]
Notes:
A high-refractive-index polymer is a polymer that has a refractive index greater than 1.50. Such materials are required for anti-reflective coating and photonic devices such as light emitting diodes (LEDs) and image sensors.
2. The Helium atoms that have lost two electrons are called ________?
[A] Alpha rays
[B] Beta rays
[C] Gamma rays
[D] None of the above
Show Answer
Correct Answer: A [Alpha rays]
Notes:
Helium atoms that have lost two electrons are called alpha rays. Alpha rays are also called alpha particles or alpha radiation. Alpha particles are made up of two protons and two neutrons bound together into a particle that is identical to a helium-4 nucleus.
Alpha particles are named after the first letter in the Greek alphabet, α. They were the first nuclear radiation to be discovered.
When a helium atom loses its electrons, it is left with only the nucleus. This is called an alpha particle.
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
Show Answer
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. Under standard conditions, which of the following is the most stable form of carbon?
[A] Charcoal
[B] Graphite
[C] Diamond
[D] Amorphous Carbon
Show Answer
Correct Answer: B [Graphite]
Notes:
Under standard conditions, Graphite is the most stable form of carbon. It is commonly used in pencils and lubricants due to its layered structure. These layers can move over each other, making graphite soft and slippery. Besides Graphite, other forms of carbon are diamond, charcoal, and amorphous carbon, each with unique properties and applications.
5. 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.
6. Which of the following chemicals is also known as "butter of tin"?
[A] Stannic chloride
[B] Sodium perborate
[C] Potassium nitrate
[D] Magnesium hydroxide
Show Answer
Correct Answer: A [ Stannic chloride]
Notes:
“Butter of Tin” is also known as tin tetrachloride pentahydrate. It is called “butter of tin” because of its physical appearance. Its chemical formula is SnCl4*5H2O or [SnCl4 (H2O)]*3H2O.
7. What do we call the compounds having identical molecular formula but different structures?
[A] Functional isomers
[B] Structural isomers
[C] Mirror isomers
[D] Branched isomers
Show Answer
Correct Answer: B [Structural isomers]
Notes:
The compounds with identical molecular formula but different structures are called structural isomers.
8. In which of the following cases, components can be separated using a separating funnel?
[A] Mixture of acetone and water
[B] Mixture of oil and water
[C] Different gases in the air
[D] None of the above
Show Answer
Correct Answer: B [Mixture of oil and water]
Notes:
A separating funnel can be used to separate the components of the mixture of immiscible liquids. Components in the mixture of oil and water can be separated using this method.
9. Choose the incorrect statement:
[A] Epsom salt is an ore containing Sodium
[B] Bauxite is an ore of Aluminium
[C] Asbestos is an ore containing Calcium
[D] Milarite mineral contains Nickel
Show Answer
Correct Answer: A [Epsom salt is an ore containing Sodium]
Notes:
Epsom salt is an ore containing Magnesium. It is also known as the heptahydrate sulfate mineral. Its chemical formula is MgSO4·7H2O.
10. Which of the following statements is correct about Beta-decay?
[A] In β+decay, Mass number increases by 2
[B] In β−decay, Mass number decreases by 2
[C] In β−decay, the atomic number increases by 1
[D] None of the above
Show Answer
Correct Answer: C [In β−decay, the atomic number increases by 1]
Notes:
In both β− and β+ decay, the mass number A remains unchanged. In β− decay, the atomic number of the nucleus goes up by 1, while in β+ decay, the atomic number goes down by 1.
