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 qualities of iron ore is best based upon iron content?
[A] Magnetite
[B] Hematite
[C] Limonite
[D] Siderite
Show Answer
Correct Answer: A [Magnetite]
Notes:
Magnetite, followed by Hematite – Limonite – Siderite
2. What are the main constituents of LPG?
[A] Methane, Hexane, Ethane
[B] Methane, Butane, Propane
[C] Ethane, Pentane, Hexane
[D] Ethane, Methane, Pentane
Show Answer
Correct Answer: B [Methane, Butane, Propane]
Notes:
LPG is composed hydrocarbons containing three or four carbon atoms. The normal components of LPG thus, are propane (C3H8), butane (C4H10) and Methane (CH4). Small concentrations of other hydrocarbons may also be present.
3. What is the primary use of Phenolphthalein in chemistry?
[A] A Solvent
[B] A Dye
[C] A Catalyst
[D] A Detergent
Show Answer
Correct Answer: B [A Dye]
Notes:
Phenolphthalein is commonly employed as a pH indicator in titrations due to its distinct color change in varying pH levels. At pH 8.2, it appears colorless but turns pink as the pH increases to 10. It is not used as a solvent, catalyst or detergent. It also finds applications in forensic science for detecting latent blood stains.
4. Under standard conditions, which of the following is the most stable form of carbon?
[A] Charcoal
[B] Graphite
[C] Diamond
[D] Amorphous Carbon
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Correct Answer: B [Graphite]
Notes:
Under standard conditions, Graphite is the most stable form of carbon. It is commonly used in pencils and lubricants due to its layered structure. These layers can move over each other, making graphite soft and slippery. Besides Graphite, other forms of carbon are diamond, charcoal, and amorphous carbon, each with unique properties and applications.
5. The Potassium graphite and Calcium Graphite can be mostly used as which among the following?
[A] Moderators
[B] Semiconductors
[C] Superconductors
[D] Lubricants
Show Answer
Correct Answer: C [Superconductors]
Notes:
Potassium graphite and calcium graphite are primarily used as superconductors. Superconductors are materials that can conduct electricity without resistance when cooled below a certain temperature. Graphite, particularly when doped with potassium or calcium, exhibits enhanced superconducting properties. Notably, the discovery of high-temperature superconductors in the 1980s revolutionized the field, leading to applications in magnetic levitation and advanced electronic devices.
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 radical is also known as the “atmospheric detergent” ?
[A] Chlorine radical
[B] Hydroxyl radical
[C] Methyl radical
[D] Ozone radical
Show Answer
Correct Answer: B [ Hydroxyl radical]
Notes:
One of the most important chemical components of the troposphere is the ‘hydroxyl radical’: a highly reactive substance composed of an oxygen and a hydrogen atom, denoted ‘OH’. Hydroxyl radicals react with just about any other trace gas they encounter, removing them from the atmosphere.For example, OH combines with toxic carbon monoxide to generate carbon dioxide. In this sense, OH ‘cleans up’ the troposphere, and is sometimes called the detergent of the atmosphere.
8. 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.
9. Which of the following is NOT correct about Phosphine?
[A] The chemical formula is PH3
[B] The electronic structure is like Ammonia
[C] It is odorless
[D] it is used as a dopant in semiconductor industries
Show Answer
Correct Answer: C [It is odorless]
Notes:
Phosphine is PH3. The electronic structure of Phosphine (pyramidal structure) is like Ammonia. It is a colourless gas and has a spoiled fish smell. It is used as a dopant in semiconductor industries.
10. Which of the following is not a mixture?
[A] Ocean water
[B] Table salt
[C] Air
[D] Soil
Show Answer
Correct Answer: B [Table salt]
Notes:
The composition of a mixture is variable whereas it is fixed for a compound. Table salt i.e. Sodium chloride is a compound and not a mixture.
