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 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.
2. Who among the following scientists had discovered Radium?
[A] Marie Sklodowska-Curie and Pierre Curie
[B] André-Louis Debierne
[C] Kasimir Fajans
[D] Oswald Helmuth Göhring
Show Answer
Correct Answer: A [Marie Sklodowska-Curie and Pierre Curie ]
Notes:
Radium is a chemical element with the symbol Ra and atomic number 88. Radium was discovered by Marie Sklodowska Curie, a Polish chemist, and Pierre Curie, a French chemist, in 1898.
3. What happens to water’s vapor pressure when heated?
[A] It increases
[B] It decreases
[C] It first increases then decreases
[D] No change
Show Answer
Correct Answer: A [It increases]
Notes:
Vapor pressure of water increases as its temperature rises. At 25°C, water’s vapor pressure is approximately 23.8 mmHg, while at 100°C it reaches 760 mmHg. When a liquid is heated, kinetic energy of molecules grows, allowing more to escape as vapor and thus increasing vapor pressure.
4. 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.
5. 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.
6. Which of the following is NOT correct about the use of Quick lime?
[A] Manufacturing of cement
[B] Manufacture of sodium carbonate
[C] Purification of sugar
[D] used to extinguish fire
Show Answer
Correct Answer: D [used to extinguish fire]
Notes:
(i) It is an important primary material for manufacturing cement and is the cheapest form of alkali. (ii) It is used in the manufacture of sodium carbonate from caustic soda. (iii) It is employed in the purification of sugar and in the manufacture of dye stuffs.
7. What do we call the process of converting an ore into its oxide by heating it in a limited supply of air below its melting point?
[A] Roasting
[B] Calcination
[C] Leaching
[D] Liquation
Show Answer
Correct Answer: B [Calcination]
Notes:
Calcination is the process of converting an ore into its oxide by heating it in a limited supply of air or in absence of air, below its melting point. It is used to convert the concentrated ore to its oxide.
8. Which of the following equation represents combination of Hydrogen gas with nitrogen to form ammonia?
[A] 2H2 + N –> NH3
[B] 2H + N3 –> NH3
[C] 3H2 + N2 –> 2NH3
[D] None of the above
Show Answer
Correct Answer: C [3H2 + N2 –> 2NH3]
Notes:
3H2 + N2 –> 2NH3 is the balance equation which represents combination of Hydrogen gas with nitrogen to form ammonia.
9. Which of the following quantum numbers is represented by a period of the modern periodic table?
[A] Principal quantum number
[B] Azimuthal quantum number
[C] Magnetic quantum number
[D] None of the above
Show Answer
Correct Answer: A [Principal quantum number]
Notes:
The Period in the modern periodic table indicates the value of ‘n’ (principal quantum number) for the outermost or valence shell.
10. What is the bond angle in case of Ammonia molecule?
[A] 120°
[B] 150°
[C] 66°
[D] 107°
Show Answer
Correct Answer: D [107°]
Notes:
The bond angle in case of Ammonia molecule is 107° and the molecular geometry is trigonal pyramidal. The number of bond pairs in Ammonia is 3 and lone pair is 1.
