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. Which of the following is an alkaline earth metal?
[A] Pottasium
[B] Lead
[C] Copper
[D] Calcium
Show Answer
Correct Answer: D [Calcium ]
Notes:
The six elements in column 2 of the Periodic table are called Alkaline Earth Metals. These include Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra).
3. Which among the following oxides cause the Acid rain?
[A] Carbon monoxide and carbon dioxide
[B] Nitrous oxide and sulphur dioxide
[C] Carbon dioxide and nitrous oxide
[D] Sulphur dioxide and carbon monoxide
Show Answer
Correct Answer: B [Nitrous oxide and sulphur dioxide ]
Notes:
Acid rain is caused by nitrous oxides (NOx) and sulfur dioxide (SO2) emissions, which react with water molecules in the atmosphere to form nitric and sulfuric acids. These acids then fall to the ground in rain, snow, fog, or dust particles.
4. What happens to the weight of Iron, when it rusts?
[A] Increases for long time
[B] Decreases then increases
[C] Increases then decreases
[D] Remains the same
Show Answer
Correct Answer: C [Increases then decreases]
Notes:
When iron or any other metal oxidizes, oxygen from the air combines with the iron to make iron oxide or rust. So, weight of the bar increases, due to the increased weight of oxygen which has combined with the iron. over time, the weight of the iron bar will tend to decrease, due to factors related more to erosion than to chemistry.
5. Which gas is produced when an alkali metal, like Lithium or Sodium, reacts with water?
[A] Oxygen
[B] Hydrogen
[C] Ozone
[D] Carbon Dioxide
Show Answer
Correct Answer: B [Hydrogen]
Notes:
The reaction of alkali metals with water produces Hydrogen gas. These metals are part of the first group on the period table and include lithium, sodium, and potassium. They are known for their vigorous reactions with water, which results in the liberation of hydrogen gas. Along with the gas, this reaction also forms a basic alkali metal hydroxide, which gives the solution its characteristic basic or alkaline properties.
6. Cassiterite is a primary ore of which of the following elements?
[A] Iron
[B] Zinc
[C] Copper
[D] Tin
Show Answer
Correct Answer: D [Tin]
Notes:
Cassiterite is a mineral that is a significant ore of tin. It is also known as tin oxide. Although rare, its key characteristic is its high specific gravity that makes it easy to separate it from other materials. Tin, which is extracted from Cassiterite, is commonly used in making alloys, punches, and cutting tools.
7. Which among the following is Fool’s Gold?
[A] Copper Sulphate
[B] Iron Sulfide
[C] Brass
[D] Silver Bromide
Show Answer
Correct Answer: B [Iron Sulfide]
Notes:
The mineral pyrite or iron pyrite, also known as fool’s gold, is an iron sulfide with the chemical formula FeS2 (iron (II) disulfide). “Fool’s Gold” is technically known as pyrite or iron sulfide (FeS2) and is one of the most common sulfide minerals. Its nickname is “Fool’s Gold,” but it often contains a surprising amount of gold.
8. Argon is the third most common gas in the Earth’s atmosphere, at 0.93%. This gas is generated due to decay of which among the following isotopes in the Earth’s crust ?
[A] K-40
[B] Ca-40
[C] Ca-48
[D] K-41
Show Answer
Correct Answer: A [K-40]
Notes:
Potassium-40 is a radioactive isotope of potassium with a long half-life of 1.251×10⁹ years. The decay of this particular isotope explains the large abundance of argon (0.93%) in the Earth’s atmosphere.
9. 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.
10. Which among the following impurity in drinking water causes the “Bamboo Spine” disorder?
[A] Nitrate
[B] Fluorides
[C] Arsenic
[D] Sulphides
Show Answer
Correct Answer: B [ Fluorides]
Notes:
Ankylosing Spondylitis is a chronic, inflammatory arthritis and autoimmune disease that mainly affects joints in the spine and the sacroiliac joints in the pelvis. It tends to affect the spine and in late stages, the spine will fuse and this has given rise to the term “bamboo spine”. It is mainly caused due to impurities in drinking water associated with fluorides.
