Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. Dalton’s name is associated with which of the following terms?
[A] Electron
[B] Proton
[C] Atom
[D] Neutron
Show Answer
Correct Answer: C [Atom]
Notes:
John Dalton introduced the atomic theory into chemistry. The main points of Dalton’s atomic theory are (1) Elements are made of extremely small particles called atoms. (2) Atoms of a given element are identical in size, mass and other properties; atoms of different elements differ in size, mass and other properties.(3) Atoms cannot be subdivided, created or destroyed. (4) Atoms of different elements combine in simple whole-number ratios to form chemical compounds. (5) In chemical reactions, atoms are combined, separated or rearranged.
2. Which among the following is major component of Gobar Gas?
[A] Butane
[B] Ethane
[C] Propane
[D] Metahne
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Correct Answer: D [Metahne]
Notes:
Gobar Gas or Biogas is mostly methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulfide (H2S), moisture and siloxanes.
3. What happens to ozone’s volume when it is heated?
[A] Increases
[B] Decreases
[C] Remains unchanged
[D] First increases, then decreases
Show Answer
Correct Answer: A [Increases]
Notes:
According to Charles’s Law, for gases at constant pressure, volume increases with temperature. Heating ozone increases the kinetic energy of molecules, expanding its volume if pressure is constant. Ozone (O₃) behaves like other gases, expanding when heated. This law applies to all ideal gases and ozone approximates ideal behavior under moderate conditions.
4. What is the common name of Calcium Sulphate Hemihydrate?
[A] Bleaching powder
[B] Slaked lime
[C] Plaster of paris
[D] Detergent
Show Answer
Correct Answer: C [Plaster of paris]
Notes:
Plaster of Paris is calcium sulphate hemihydrate. The formula is given as, CaSO4.1/2 H2O or (2 CaSO4) . H2O. The powder is called plaster of Paris, because the gypsum which was used to get the powder was mainly found in Paris.
5. The chemical oxygen demand COD test is commonly used to measure which of the following?
[A] amount of organic compounds in water
[B] amount of oxygen in water
[C] amount of oxygen in a chemical
[D] amount of oxygen used in a oxygenation process
Show Answer
Correct Answer: A [amount of organic compounds in water]
Notes:
chemical oxygen demand is a measure of water quality and is amount of organic pollutants found in surface water. Potassium permanganate has been used for many years to measure COD
6. Which of the following alkali metal ions has the highest hydration enthalpy?
[A] Lithium
[B] Sodium
[C] Potassium
[D] Caesium
Show Answer
Correct Answer: A [Lithium]
Notes:
Lithium ions has maximum degree of hydration and for this reason lithium salts are mostly hydrated.
7. What is Rose metal?
[A] It is an alloy of Nickel, Tin and Zinc
[B] It is an alloy of Bismuth, Copper and Palladium
[C] It is an alloy of Palladium, Tin and Lead
[D] It is an alloy of Bismuth, Tin and Lead
Show Answer
Correct Answer: D [It is an alloy of Bismuth, Tin and Lead]
Notes:
Rose metal is an alloy of Bismuth, Tin and Lead. It’s a fusible alloy with low melting point commonly used for soldering.
8. Which of the following metals is extracted and refined in the Mond’s process?
[A] Cobalt
[B] Bismuth
[C] Nickel
[D] Copper
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Correct Answer: C [Nickel]
Notes:
The Mond process is a technique to extract and purify nickel. It is also known as the carbonyl process. In this, nickel is heated in a stream of carbon monoxide forming a volatile complex, nickel tetracarbonyl.
9. What can be the maximum number of electrons in a shell, if principal quantum number is n?
[A] n
[B] n2
[C] 2n2
[D] 3n3
Show Answer
Correct Answer: C [2n2]
Notes:
The general formula is that the nth shell can hold up to 2n2 electrons. For example: for L shell n =2, so maximum number of electrons will be 2(22) i.e. 8.
10. What is the multiplication factor when the nuclear reactor is said to be critical?
[A] 0
[B] 1
[C] 2
[D] 10
Show Answer
Correct Answer: B [1]
Notes:
The multiplication factor is the measure of the growth rate of the neutrons in the reactor. For K = 1, the operation of the reactor is said to be critical.
