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 of the following is not a common use of Graphite?
[A] Manufacturing of electrodes
[B] As a lubricant
[C] Manufacturing of crucibles
[D] In glass cutting
Show Answer
Correct Answer: D [In glass cutting]
Notes:
Graphite is renowned for its conspicuous uses owing to its unique properties like its ability to conduct electricity, which makes it ideal for electrode manufacturing. It’s also used as a lubricant and in the production of crucibles, thanks to its high melting point. However, it isn’t used in glass cutting.
2. Which of the following processes commonly use the method of adsorption?
[A] Scrubbers manufacturing
[B] Purification of solid substances
[C] Chromatography
[D] Purification of liquid substances
Show Answer
Correct Answer: C [Chromatography]
Notes:
Adsorption, the binding of gas or liquid particles to a solid surface, is often used in chromatography – a laboratory technique for the separation of a mixture. This process is critical as it allows the separation of the compounds in the mixture, thereby enabling further analysis or purification. Apart from chromatography, adsorption is also used in scrubbers and purification of solids and liquids.
3. Which among the following is the most important characteristic of Noble metals?
[A] Luster
[B] Non reactive nature
[C] Preciousness
[D] Rare availability
Show Answer
Correct Answer: B [Non reactive nature]
Notes:
Noble metals, such as gold, silver, and platinum, are primarily characterized by their non-reactive nature. This means they resist oxidation and corrosion, making them ideal for use in jewelry and electronics. Unlike base metals, noble metals do not easily form compounds with other elements, which is why they maintain their luster and appearance over time. Their rarity and preciousness are secondary characteristics, but their chemical stability is what truly defines them as noble.
4. Which among the following is the lowest atomic number element without any stable isotopes?
[A] Technetium
[B] Molybdenum
[C] Ruthenium
[D] Niobium
Show Answer
Correct Answer: A [Technetium]
Notes:
The correct answer is Technetium. It has the atomic number 43 and is the lowest atomic number element without any stable isotopes. All of its isotopes are radioactive, with Technetium-98 being the most stable, having a half-life of about 4.2 million years. Technetium was first artificially produced in 1937 by Carlo Perrier and Emilio Segrè, making it the first element to be artificially created.
5. Which among the following makes Chile saltpetre different from saltpetre?
[A] Nitrate
[B] Sodium
[C] Magnesium
[D] Calcium
Show Answer
Correct Answer: B [Sodium]
Notes:
Chile saltpetre, or sodium nitrate (NaNO3), differs from regular saltpetre, which typically refers to potassium nitrate (KNO3). Chile saltpetre is primarily composed of sodium, while traditional saltpetre contains potassium. Historically, Chile saltpetre was extensively mined in the Atacama Desert and was crucial for fertilizer and explosives in the 19th century.
6. 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
7. Which of the following chemicals is also known as “Chinese snow”?
[A] Silver iodide
[B] Potassium nitrate
[C] Ammonium chloride
[D] Sodium phosphate
Show Answer
Correct Answer: B [ Potassium nitrate]
Notes:
Potassium nitrate is one of several nitrogen-containing compounds collectively referred to as saltpetre or saltpetre. It is also known as “Chinese snow”. Major uses of potassium nitrate are in fertilizers, rocket propellants and fireworks.
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 also known as Alumina?
[A] AlO2
[B] Al2O3
[C] Al2O4
[D] Al2CO2
Show Answer
Correct Answer: B [Al2O3]
Notes:
Alumina is the common name given to aluminum oxide (Al2O3). It is produced from bauxite to get pure aluminium metal.
10. Which of the following is / are correct statements about methane?
- The largest reservoir of methane on earth is under the permafrost at arctic and Antarctic
- Methane has a tetrahedral structure and also known as Hydrogen Carbide
- Methane can be produced by Serpentinite method
Select the correct option from codes given below:
[A] Only 1 & 2
[B] Only 1 & 3
[C] Only 2 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: C [Only 2 & 3 ]
Notes:
Methane has a tetrahedral structure, which is multiplanar, in which carbon atom lies at the centre and the four hydrogen atoms lie at the four corners of a regular tetrahedron. The largest reservoir of methane on earth is under the seafloor. Serpentinite method is a method of producing Methane by inorganic method.
