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 among the following is known as Quick Lime?
[A] CaO
[B] CaCO2
[C] Ca(OH)2
[D] CaCl2
Show Answer
Correct Answer: A [CaO]
Notes:
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline crystalline solid at room temperature.
2. Which among the following types of glasses contains Cerium and other rare earths and has a high absorption of ultraviolet rays?
[A] Crookes Glass
[B] Pyrex Glass
[C] Flint Glass
[D] Crown Glass
Show Answer
Correct Answer: A [Crookes Glass]
Notes:
Crookes glass comprises Cerium oxide (CiO2) which sharply absorbs the ultraviolet rays from the sunlight. It is used in making lenses of eye glasses.
3. Which among the following gas has lowest auto-ignition temperature?
[A] Methane
[B] Hydrogen
[C] Ethylene
[D] Carbon Di Sulphide
Show Answer
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
4. Which among the following kinds of Chemical reactions cause the rocks turn red or yellowish?
[A] Hydration
[B] Oxidation
[C] Carbonation
[D] Exfoliation
Show Answer
Correct Answer: B [Oxidation]
Notes:
The correct answer is Oxidation. This reaction occurs when minerals in rocks, particularly iron-bearing minerals, react with oxygen. This process can lead to the formation of iron oxides, which give rocks a reddish or yellowish hue. For example, rusting of iron in rocks is a common oxidation reaction. Oxidation is a important weathering process, contributing to soil formation and landscape changes.
5. Haber Process is used to produce which among the following?
[A] Potash
[B] Ammonia
[C] Urea
[D] Nitrates
Show Answer
Correct Answer: B [Ammonia]
Notes:
The Haber Process is an industrial method for synthesizing ammonia from nitrogen and hydrogen gases. Developed by Fritz Haber and Carl Bosch in the early 20th century, it operates under high pressure and temperature, using an iron catalyst. Ammonia produced is crucial for fertilizers, supporting global agriculture. The process importantly increased food production, earning Haber the Nobel Prize in Chemistry in 1918.
6. Consider the following:
- Hydrogen (H2)
- Carbon monoxide (CO)
- Carbon dioxide (CO2)
- Methane (CH4)
Which of the above is/are component(s) of high-quality (100% pure) Syngas?
[A] 1 Only
[B] 1 & 2 Only
[C] 1, 2 & 3 Only
[D] 1, 2, 3 & 4
Show Answer
Correct Answer: B [ 1 & 2 Only]
Notes:
The high-quality (100% Pure) Syngas has the main components of (H2 + CO)
7. Which of the following compound of sodium is generally prepared by Solvay process?
[A] Sodium Carbonate
[B] Sodium Hydroxide
[C] Sodium Chloride
[D] All of the above
Show Answer
Correct Answer: A [Sodium Carbonate]
Notes:
Sodium carbonate is generally prepared by Solvay Process.
8. Which of the following is NOT correct about Alkynes?
[A] They contain at least two triple bond between two carbon atoms
[B] The number of hydrogen atoms is less in alkynes as compared to alkenes
[C] The general formula of Alkynes is CnH2n–2
[D] All are correct
Show Answer
Correct Answer: A [They contain at least two triple bond between two carbon atoms]
Notes:
Alkynes contain at least one triple bond between two carbon atoms. The number of hydrogen atoms is less in alkynes as compared to alkenes or alkanes. Their general formula is CnH2n–2.
9. Which of the following is correct about ozone?
[A] it is a red coloured gas
[B] it is odourless
[C] it is harmless in small concentrations
[D] All of the above
Show Answer
Correct Answer: C [it is harmless in small concentrations]
Notes:
Pure ozone is a pale blue gas, dark blue liquid and violet-black solid. Ozone has a characteristic smell and in small concentrations it is harmless. However, if the concentration rises above about 100 parts per million, breathing becomes uncomfortable resulting in headache and nausea.
10. Which of these is an ore of Aluminium?
[A] Corundum
[B] Kieserite
[C] Pitch blende
[D] All of the above
Show Answer
Correct Answer: A [Corundum]
Notes:
Corundum is an ore of Aluminium. It is a crystalline form of aluminium oxide. Kieserite is an ore of Magnesium and Pitch blende is an ore of Uranium.
