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 elements are generally find in free state?
[A] Group 11 elements
[B] Group 12 elements
[C] Group 13 elements
[D] Group 14 elements
Show Answer
Correct Answer: A [Group 11 elements ]
Notes:
Group 11 is also known as the coinage metals, due to their former usage. They were most likely the first three elements discovered. Copper, silver, and gold all occur naturally in elemental form.
2. Argon is the third most common gas in the Earth’s atmosphere, at 0.93%. This gas is generated due to decay of which among the following isotopes in the Earth’s crust ?
[A] K-40
[B] Ca-40
[C] Ca-48
[D] K-41
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Correct Answer: A [K-40]
Notes:
Potassium-40 is a radioactive isotope of potassium with a long half-life of 1.251×10⁹ years. The decay of this particular isotope explains the large abundance of argon (0.93%) in the Earth’s atmosphere.
3. The Potassium graphite and Calcium Graphite can be mostly used as which among the following?
[A] Moderators
[B] Semiconductors
[C] Superconductors
[D] Lubricants
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Correct Answer: C [Superconductors]
Notes:
Potassium graphite and calcium graphite are primarily used as superconductors. Superconductors are materials that can conduct electricity without resistance when cooled below a certain temperature. Graphite, particularly when doped with potassium or calcium, exhibits enhanced superconducting properties. Notably, the discovery of high-temperature superconductors in the 1980s revolutionized the field, leading to applications in magnetic levitation and advanced electronic devices.
4. What happens to the non-metallic character of elements in the p-block of the periodic table?
[A] non-metallic character decreases down the group
[B] non-metallic character increases down the group
[C] No fix pattern
[D] None
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Correct Answer: A [non-metallic character decreases down the group]
Notes:
The non-metallic character of elements decreases down the group. In fact, the heaviest element in each p-block group is the most metallic in nature.
5. Which of the following defines the solubility of a solution?
[A] amount of the solvent present in the saturated solution
[B] amount of the solute present in the saturated solution
[C] amount of the solute per amount of solute in the solution
[D] difference of amount of solvent and the amount of solute
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Correct Answer: B [amount of the solute present in the saturated solution]
Notes:
The amount of the solute present in the saturated solution at a given temperature is called its solubility.
6. Which of the following is the balance equation for Aluminium + Copper chloride – Aluminium chloride + Copper?
[A] 2Al + 2CuCl3 – 2AlCl3 + Cu
[B] Al + 2CuCl2 – AlCl3 + 2Cu
[C] 2Al + 3CuCl2 – 2AlCl3 + 3Cu
[D] None of the above
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Correct Answer: C [2Al + 3CuCl2 – 2AlCl3 + 3Cu]
Notes:
2Al + 3CuCl2 – 2AlCl3 + 3Cu is the balanced equation of Aluminium + Copper chloride – Aluminium chloride + Copper.
7. What is the sum of powers of the concentration of the reactants called as?
[A] Order of reaction
[B] Stage of reaction
[C] Zone of reaction
[D] None of the above
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Correct Answer: A [Order of reaction]
Notes:
The sum of powers of the concentration of the reactants in the rate law expression is known as the order of that chemical reaction.
8. Which of the following is correct about Mendeleev’s Periodic Table?
[A] Argon is placed before Potassium
[B] Cobalt is placed before Nickel
[C] Tellurium is placed before iodine
[D] All of the above
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Correct Answer: D [All of the above]
Notes:
All statements represent the anomalous pairs of elements in Mendeleev’s Periodic Table. The atomic mass of argon is 39.9 and that of potassium 39.1. But argon is placed before potassium in the periodic table. Similarly, Tellurium is placed before iodine and Cobalt is placed before Nickel.
9. What is the period and group number of Silicon (Z=14) in the periodic table?
[A] 2nd Period, 4th Group number
[B] 2nd Period, 14th Group number
[C] 3rd Period, 4th Group number
[D] 3rd Period, 14th Group number
Show Answer
Correct Answer: D [3rd Period, 14th Group number]
Notes:
Silicon has an atomic number 14 and the outer electronic configuration is 3s2 3ps2. It is placed at the 3rd Period and 14th Group number.
10. Choose the correct statement about d-block elements:
[A] These are the elements of Group 3 to 10
[B] All of them are metals
[C] Both a and b
[D] None
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Correct Answer: B [All of them are metals]
Notes:
d-block elements are the elements of Group 3 to 12 in the centre of the Periodic Table. All of them are metals. These are characterised by the filling of inner d orbitals by electrons.
