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 scientists had discovered Radium?
[A] Marie and Pierre Curie
[B] Andre-Louis Debierne
[C] Kasimir Fajans
[D] Oswald Helmuth Gohring
Show Answer
Correct Answer: A [Marie and Pierre Curie]
Notes:
Radium(Ra) with atomic number 88 was discovered by Marie and Pierre Curie in 1898 as Radium Chloride. However, it was Radium was isolated in its metallic state by Marie Curie and André-Louis Debierne through the electrolysis of radium chloride in 1911.
2. 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.
3. What type of fiber is Rayon considered?
[A] A synthetic fiber
[B] A natural fiber
[C] A semi-synthetic fiber
[D] A synthetic detergent
Show Answer
Correct Answer: C [A semi-synthetic fiber]
Notes:
Rayon is considered a semi-synthetic fiber. It is made by regenerating natural materials into a usable form. Rayon fibers are derived from cellulose obtained from wood or related agricultural products. It was first commercially produced in 1905 by the Swiss firm J. R. Geigy, originally under the name “artificial silk”
4. The atomic weight of Chlorine is 35. It consists of _______?
[A] 17 Protons + 18 Neutrons
[B] 17 Neutrons + 18 protons
[C] 17 Neutrons + 17 Protons + 1 electron
[D] None of the above
Show Answer
Correct Answer: A [17 Protons + 18 Neutrons]
Notes:
Chlorine has an atomic number of 17, meaning it has 17 protons. Its atomic weight is approximately 35, which indicates it typically has 18 neutrons (35 – 17 = 18). Therefore, the correct composition is 17 protons and 18 neutrons. Chlorine is a halogen and exists primarily as two stable isotopes: Chlorine-35 and Chlorine-37.
5. Normal” rainfall is slightly acidic (and a pH of 5.6 has been assigned which might be somewhere near 5 ) because of the presence of _______?
[A] Nitric Oxide
[B] Sulphuric Acid
[C] Nitric Acid
[D] Carbonic Acid
Show Answer
Correct Answer: D [Carbonic Acid]
Notes:
Normal rainfall is slightly acidic due to the presence of carbonic acid, which forms when carbon dioxide (CO2) dissolves in water. The pH of normal rainwater is typically around 5.6, making it mildly acidic. This natural acidity is a result of the CO2 in the atmosphere, which is produced by respiration, combustion, and other natural processes.
6. 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.
7. Haber Process is used to produce which among the following?
[A] Potash
[B] Ammonia
[C] Urea
[D] Nitrates
Show Answer
Correct Answer: B [Ammonia]
Notes:
The Haber Process is an industrial method for synthesizing ammonia from nitrogen and hydrogen gases. Developed by Fritz Haber and Carl Bosch in the early 20th century, it operates under high pressure and temperature, using an iron catalyst. Ammonia produced is crucial for fertilizers, supporting global agriculture. The process importantly increased food production, earning Haber the Nobel Prize in Chemistry in 1918.
8. Why most of the aromatic hydrocarbons burn with a sooty flame?
[A] Because the carbon-hydrogen ratio in aromatic compounds is high
[B] Because of the presence of the strong carbon-carbon bonds
[C] Because, hydrocarbons are unsaturated
[D] Because the carbon-hydrogen ratio in aromatic compounds is low
Show Answer
Correct Answer: A [ Because the carbon-hydrogen ratio in aromatic compounds is high]
Notes:
Because the carbon-hydrogen ratio in aromatic compounds is high.
9. What is the atomic number of Barium?
[A] 54
[B] 56
[C] 58
[D] 60
Show Answer
Correct Answer: B [56]
Notes:
The atomic number of barium is 56.
10. Brass is an alloy of which of the following metals?
[A] Copper and Tin
[B] Copper and Zinc
[C] Lead and Tin
[D] Zinc and Nickel
Show Answer
Correct Answer: B [Copper and Zinc]
Notes:
Brass is an alloy of copper and zinc (Cu and Zn). Lead is often added in concentrations of around 2% to enhance the machinability of brass.
