Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. The term “white coal” sometimes referred to which of the following?
[A] Geothermal Electricity
[B] Wind Energy
[C] Hydroelectricity
[D] Biomass Energy
Show Answer
Correct Answer: C [Hydroelectricity]
Notes:
The term white coal was used for Hydroelectricity, particularly in Europe, because of its capability to produce more energy than any other source except coal. The term was coined by a French Engineer Aristide Bèrges.
2. Which among the following methods can be used to remove the permanent hardness in water due to calcium or magnesium sulphates?
[A] Sulphonate method
[B] Nitrate method
[C] Zeolite method
[D] None of these
Show Answer
Correct Answer: C [Zeolite method ]
Notes:
Zeolite is hydrated Sodium Alumino-silicate capable of exchanging reversible Sodium ions for hardness producing ions in water. It is also use as softening of water. It is used to remove the permanent hardness in water due to Calcium or Magnesium sulphates.
3. Which among the following are constituents of Brass?
[A] Zinc and Copper
[B] Iron and Zinc
[C] Copper and Nickel
[D] Iron and Copper
Show Answer
Correct Answer: A [Zinc and Copper ]
Notes:
Brass is an alloy of Copper and Zinc, in proportions which can be varied to achieve varying mechanical and electrical properties. The proportions of Zinc and Copper can vary to create different types of brass alloys with varying mechanical and electrical properties.
4. What is the primary event that occurs during an oxidation reaction?
[A] Electrons are gained
[B] Electrons are lost
[C] Protons are gained
[D] Protons are lost
Show Answer
Correct Answer: B [Electrons are lost]
Notes:
Oxidation is a chemical reaction in which an atom, ion, or molecule loses an electron to another substance. So, the correct answer is “Electrons are lost”. This phenomenon is often observed in various chemical and biological systems. Understanding this important process can allow us to gain insights in fields ranging from biology to materials science.
5. 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.
6. Which among the following gives hissing sound when dissolved into H2O?
[A] CaCO2
[B] Ca(OH)2
[C] CaO
[D] CaCl2
Show Answer
Correct Answer: C [CaO]
Notes:
The correct answer is CaO (calcium oxide), which is also known as quicklime. When CaO is dissolved in water, it reacts exothermically to form calcium hydroxide (Ca(OH)2), producing a hissing sound due to the rapid release of heat and steam. This reaction is a classic example of a vigorous exothermic reaction in chemistry. Calcium oxide is commonly used in construction and as a drying agent.
7. Carbon monoxide poisoning is the most common type of fatal air poisoning in many parts of the world. What makes it such a fatal gas?
[A] CO dissolves in cytoplasm and functions as an inhibitor of the crucial enzymes for metabolism
[B] CO competes with Haemoglobin for Oxygen intake
[C] CO dissolves in blood Plasma and spreads toxicity
[D] CO converts into Carbon Dioxide in presence of water in Blood
Show Answer
Correct Answer: B [ CO competes with Haemoglobin for Oxygen intake]
Notes:
Carbon monoxide is colourless, odourless, and tasteless, but highly toxic because it combines with haemoglobin to produce carboxyhemoglobin, which usurps the space in haemoglobin that normally carries oxygen, but is ineffective for delivering oxygen to bodily tissues. Concentrations as low as 667 ppm may cause up to 50% of the body’s hemoglobin to convert to carboxyhemoglobin. The impact is irreversible and that is why that even after available of oxygen, the carboxyhemoglobin does not allow the Oxygen to be taken up.
8. Which of the following laws states that the partial vapour pressure of each component of an ideal mixture of liquids is equal to the vapour pressure of the pure component multiplied by its mole fraction in the mixture?
[A] Raoult’s law
[B] Henry’s law
[C] Graham’s law
[D] Sievert’s law
Show Answer
Correct Answer: A [ Raoult’s law]
Notes:
Raoult’s law states that the partial vapour pressure of each component of an ideal mixture of liquids is equal to the vapour pressure of the pure component multiplied by its mole fraction in the mixture.
9. Which of the following chemicals is called Philosopher’s Wool?
[A] Brimstone
[B] Zinc oxide
[C] Magnesium hydroxide
[D] Potassium nitrate
Show Answer
Correct Answer: B [ Zinc oxide]
Notes:
The compound zinc oxide (ZnO) is called philosopher's wool. ZnO is a white powder that is insoluble in water. Zinc oxide is used as an additive in sun screens, sun lotions, in rubber manufacturing and in photocopying products. Alchemists, as part of their rituals, burn zinc in air and collect the residue, which formed into white woolly tufts. They called it Lana philosophica in Latin, meaning philosopher's wool.
10. Who gave the law of octaves for arrangement of elements?
[A] Lothar Meyer
[B] Dmitri Mendeleev
[C] John Alexander Newlands
[D] Johann Dobereiner
Show Answer
Correct Answer: C [John Alexander Newlands]
Notes:
Newland law of octaves states that If the elements are arranged in order of their increasing atomic weights, every 8th element had similar properties to the first one. It was similar as the first and eighth note in music.
