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 Gold Ring which is 50% pure. Its purity can be alternatively shown as __:
[A] 18 Carat
[B] 18 Karat
[C] 12 Carat
[D] 12 Karat
Show Answer
Correct Answer: D [ 12 Karat ]
Notes:
The carat is the common unit used to describe the mass of a gem. A 1-carat diamond, for example, has a mass of 0.20 g. The karat is the common unit used to describe the purity of a precious metal, such as gold. A 24-karat gold ring is as pure as can be. A gold ring that is 50 % pure is 12 karat.
2. Which of the following is also known as wood alcohol?
[A] Methanol
[B] Ethanol
[C] Propanal
[D] Butanol
Show Answer
Correct Answer: A [Methanol]
Notes:
Methanol (CH3OH) is also known as Wood Alcohol. It’s a solvent in many chemical processes and is a component of automobile antifreeze.
3. A cotton wick dipped in pure honey when ignited with a matchstick will ______?
[A] Burn steadily
[B] Burn with a cracking sound
[C] Not burn at all
[D] Burn producing a large amount of smoke
Show Answer
Correct Answer: A [Burn steadily]
Notes:
A cotton wick soaked in pure honey, when lit with a matchstick, will burn consistently. This is primarily due to the high sugar content of the honey acting as fuel for the flame. Contrary to common misconceptions, honey doesn’t produce much smoke or any unusual sounds during combustion.
4. PVC is a polymer of__?
[A] Propane
[B] Vinyl chloride
[C] Styrene
[D] Carbonates
Show Answer
Correct Answer: B [Vinyl chloride]
Notes:
Polyvinyl chloride (PVC) is made from the monomer vinyl chloride (CH2 =CHCl). It is used for making raincoats, handbags, toys including dolls, electrical goods and as a covering of electrical wires.
5. Acid rain is capable of damaging the buildings and historic monuments which are made up of rocks such as limestone and marble. Which among the following is the end product of such reaction?
[A] Quick Lime
[B] Calcium Carbonate
[C] Calcium Hydroxide
[D] Gypsum
Show Answer
Correct Answer: D [Gypsum]
Notes:
When sulfuric, and nitric acids, present in the acid rain reacts with the calcite in marble and limestone, it get dissolve and formed gypsum and washed off by the water. The rain can dissolve limestone and marble through direct contact.
6. Which set shows copper ores as Sulfide, Carbonate, Silicate respectively?
[A] Chalcopyrite, Azurite, Dioptase
[B] Azurite, Dioptase, Chalcopyrite
[C] Dioptase, Chalcopyrite, Azurite
[D] Dioptase, Azurite, Chalcopyrite
Show Answer
Correct Answer: A [Chalcopyrite, Azurite, Dioptase]
Notes:
Chalcopyrite is a major copper sulfide ore. Azurite is a copper carbonate mineral with formula Cu₃(CO₃)₂(OH)₂. Dioptase is a copper silicate mineral with formula CuSiO₃·H₂O. These match the deposit types in sulfide, carbonate, and silicate order respectively.
7. Which among the following alkane has largely replaced the ozone layer-depleting halomethanes in household refrigerators and freezers?
[A] Methane
[B] Propane
[C] Butane
[D] Ethane
Show Answer
Correct Answer: C [Butane]
Notes:
Isobutane, which is known in the industry as R600A has been used in several domestic refrigerators in recent times because it is an excellent refrigerant and non-ozone depleting substance with low global warming potential. The only drawback is that it is highly inflammable.
8. Double Sulphitation is the most commonly used method in India for refining of _?
[A] Crude oil
[B] Cooking oils
[C] Sugar
[D] Coal
Show Answer
Correct Answer: C [ Sugar]
Notes:
In India, the Double Sulphitation is the most commonly used method for refining of sugar. Also, it is the cheapest process of refining sugar as compared to other available process.
9. Which of these compounds is also known as wood spirit?
[A] Ethanol
[B] Methanol
[C] Propanol
[D] None of the above
Show Answer
Correct Answer: B [Methanol]
Notes:
Methanol, CH3OH, also known as ‘wood spirit’. It was produced by destructive distillation of wood.
10. Which of the following is NOT correct about Ethanol?
[A] It is a good solvent
[B] It gives out hydrogen when reacted with Sodium
[C] It is an odorless liquid
[D] All are correct
Show Answer
Correct Answer: C [It is an odorless liquid]
Notes:
Ethanol is a good solvent and reacts with sodium leading to the evolution of hydrogen. It is a colorless liquid with a slight characteristic odor.
