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 the correct set of chemical formulae of Chile Saltpetre, Saltpetre and Quick Lime?
[A] KNO3, NaNO3, CaO
[B] NaNO3, KNO3, Ca(OH)2
[C] Na(OH)2, KOH, CaO
[D] NaNO3, KNO3, CaO
Show Answer
Correct Answer: D [NaNO3, KNO3, CaO]
Notes:
Saltpetre, also spelled Saltpeter, also called Nitre, or Niter, any of three naturally occurring nitrates, distinguished as (1) ordinary saltpetre, or potassium nitrate, KNO3; (2) Chile saltpetre, cubic nitre, or sodium nitrate, NaNO3; and (3) lime saltpetre, wall saltpetre, or calcium nitrate, Ca(NO3)2.
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound.
2. Which among the following is an example of a Chemical Change?
[A] Rusting of iron
[B] Magnetisation of iron
[C] Melting of iron
[D] Heating of iron
Show Answer
Correct Answer: A [Rusting of iron ]
Notes:
Rust is an iron oxide, a usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Rusting of Iron is a chemical change.
3. What is the common name of Calcium Sulphate Hemihydrate?
[A] Bleaching powder
[B] Slaked lime
[C] Plaster of paris
[D] Detergent
Show Answer
Correct Answer: C [Plaster of paris]
Notes:
Plaster of Paris is calcium sulphate hemihydrate. The formula is given as, CaSO4.1/2 H2O or (2 CaSO4) . H2O. The powder is called plaster of Paris, because the gypsum which was used to get the powder was mainly found in Paris.
4. Consider the following:
- Cinnabar is also known as mercurblende
- The color of Cinnabar varies from dull grey to bright green
- Cinnabar is the most common source ore for refining elemental mercury
- Cinnabar is the historic source for the brilliant blue pigment termed azure
Which of the statements given above are correct?
[A] Only 1 and 3
[B] Only 2 and 4
[C] 1, 3 and 4
[D] All Four
Show Answer
Correct Answer: A [Only 1 and 3]
Notes:
Cinnabar, also known as mercurblende, is indeed the most common ore source for refining elemental mercury. However, its color range runs from scarlet to brick-red, not grey to green. It is known for providing the brilliant red or scarlet pigment known as vermilion, not a blue pigment.
5. Which of the following best describes the nature of Froth and Foam?
[A] Solid suspended in gas
[B] Liquid suspended in gas
[C] Gas suspended in liquid
[D] Gas suspended in solid
Show Answer
Correct Answer: C [Gas suspended in liquid]
Notes:
Froth and foams are examples of “gas suspended in liquid”. They are typically created when gas bubbles are dispersed in a liquid. This physical phenomenon is commonly observed in many daily life scenarios such as soap lather and carbonated drinks. Technically, they are a special case of colloid where little blobs of one liquid are dispersed in another and show the property of surface tension.
6. Which among the following gas is used in Balloons?
[A] Hydrogen
[B] Helium
[C] Nitrogen
[D] Oxygen
Show Answer
Correct Answer: B [Helium]
Notes:
The correct answer is Helium. Helium is a non-flammable, lighter-than-air gas, making it safe for use in balloons. Unlike hydrogen, which is highly flammable and poses explosion risks, helium is inert and does not react with other substances. Helium is the second most abundant element in the universe, primarily produced through nuclear fusion in stars. It was first discovered in the sun before being found on Earth.
7. Which of the following elements is not a member of the Carbon Group in the periodic table?
[A] Silicon
[B] Germanium
[C] Tin
[D] Selenium
Show Answer
Correct Answer: D [Selenium]
Notes:
The Carbon Group of the periodic table includes the elements carbon, silicon, germanium, tin, lead, and flerovium. These elements have four electrons in the outermost shell. Selenium, however, is not a part of this group. It is a member of the Chalcogens and sits beneath Oxygen in the periodic table. The element number for Selenium is 34. It is known for its photovoltaic and photocatalytic properties.
8. Consider the following:
- Copper
- Zinc
- Tin
Gun Metal is the alloy of which among the above?
[A] 1 & 2
[B] 1 & 3
[C] 2 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: D [1, 2 & 3]
Notes:
Gun metal is an alloy primarily composed of copper, tin, and zinc. Specifically, it typically contains about 88% copper, 10% tin, and 2% zinc. This alloy is known for its strength, corrosion resistance, and ability to withstand high temperatures, making it ideal for manufacturing firearms and artillery. The term “gun metal” dates back to the 15th century when it was used for cannons and other weaponry.
9. The synthetic rubber Buna is obtained from the reaction of an unsaturated hydrocarbon with ___:
[A] Sodium
[B] Magnesium
[C] Potassium
[D] Lithium
Show Answer
Correct Answer: A [Sodium]
Notes:
Buna-S is a synthetic rubber formed by co-polymerization of a mixture of 1:3 butadiene and styrene. It is obtained from Sodium.
10. Which among the following is correct statement about both rusting of iron and respiration?
[A] Both are exothermic reactions
[B] Both are endothermic reactions
[C] While Rusting is endothermic, respiration is exothermic
[D] While Rusting is exothermic, respiration is endothermic
Show Answer
Correct Answer: A [Both are exothermic reactions]
Notes:
Both are oxidation-therefore exothermic processes
