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. Which of the following is an anti-knocking compound that has been phased out in many countries so far?
[A] Lead tetrachloride
[B] Tetra Ethyl Lead
[C] Ethyl acetate
[D] None of the above
Show Answer
Correct Answer: B [Tetra Ethyl Lead ]
Notes:
Tetra Ethyl Lead (TEL) is one such component that is added to petrol to reduce its tendency to `ping’ under compression. TEL breaks down to lead at upper cylinder temperatures. Lead atoms spread around and combining with the free radicals and slowing down the reaction.
However, `Leaded’ petrol was a grave danger to the environment, as lead is a poison when it is absorbed into the body.
3. Kazimierz Funk or Casimir Funk, was a Polish biochemist, generally credited with the first formulation of the concept of which of the following ?
[A] Amino Acids
[B] DNA
[C] RNA
[D] Vitamins
Show Answer
Correct Answer: D [Vitamins]
Notes:
Kazimierz Funk (1884 – 1967) was a Polish biochemist, and one of the first to formulate the concept of Vitamins.
4. F block elements in the periodic table which are commonly called Lanthanides have the following atomic numbers:
[A] 57-70
[B] 57-71
[C] 58-71
[D] 58-70
Show Answer
Correct Answer: B [57-71]
Notes:
The correct answer is 2. The lanthanides are a series of 15 elements in the periodic table, from atomic numbers 57 (Lanthanum) to 71 (Lutetium). They are known for their similar properties and are often found together in nature. The range of atomic numbers for lanthanides is 57 to 71, not 57-70 or 58-70.
5. Which of the following chemicals is also known as "sweet oil of vitriol"?
[A] Diethyl ether
[B] Aluminium sulphate
[C] Sulphuric acid
[D] Iron(III) sulphate
Show Answer
Correct Answer: A [ Diethyl ether]
Notes:
Diethyl ether is a colourless, highly volatile & flammable organic compound. It was earlier used for anaesthesia but after the development of non-flammable drugs, its uses as anaesthetic has been reduced.
6. 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.
7. Which of the following mixture can be separated by Fractional distillation method?
[A] Air
[B] Crude oil
[C] Chlorosilanes
[D] All of the above
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Correct Answer: D [All of the above]
Notes:
Fractional distillation method is used to separate a mixture of two or more miscible liquids for which the difference in boiling points is less than 25 K. example: Air, crude oil, chlorosilanes etc.
8. What do we call the process that separates a pure solid in the form of its crystals from a solution?
[A] Crystallisation
[B] Sublimation
[C] Chromatography
[D] Distillation
Show Answer
Correct Answer: A [Crystallisation]
Notes:
Crystallisation is a process that separates a pure solid in the form of its crystals from a solution. For example: purification of the salt obtained from sea water.
9. Which of the following Metal-Ore pairs is not correct?
[A] Iron – Magnetite
[B] Aluminium – Bauxite
[C] Gold – Calaverite
[D] Calcium – Carnalite
Show Answer
Correct Answer: D [Calcium – Carnalite]
Notes:
Carnalite is an ore of Potassium. It’s a hydrated potassium magnesium chloride. The chemical formula of Carnalite is KCl. MgCl2 . 6H2O.
10. What is the half-life of Radium-223 isotope?
[A] 3 days
[B] 5 days
[C] 11.4 days
[D] 9.5 days
Show Answer
Correct Answer: C [11.4 days]
Notes:
The half-life of Radium-223 isotope is 11.4 days. The radium-226, which is a more common isotope of Radium and which wad discovered by the Curies, has a 1601-year half-life.
