Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
11. Which of the following reactions represents changing of green colour of ferrous sulphate?
[A] Double Displacement reaction
[B] Displacement reaction
[C] Combination reaction
[D] Decomposition reaction
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Correct Answer: D [Decomposition reaction]
Notes:
A reaction in which a single reactant breaks down to give simpler products is known as decomposition reaction. Ferrous sulphate crystals lose water when heated and the colour of the crystals changes. It then decomposes to ferric oxide, sulphur dioxide and sulphur trioxide.
12. What is the change in the rate constant for a chemical reaction when temperature rises by 10° C?
[A] The rate constant is constant
[B] The rate constant is nearly doubled
[C] The rate constant is nearly halved
[D] The rate constant becomes four times
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Correct Answer: B [The rate constant is nearly doubled]
Notes:
For a chemical reaction with rise in temperature by 10°, the rate constant is nearly doubled. Most of the chemical reactions are accelerated by increase in temperature.
13. How many periods and groups are there in the Modern Periodic table?
[A] 18 groups, 7 periods
[B] 16 groups, 18 periods
[C] 7 groups, 18 periods
[D] 14 groups, 8 periods
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Correct Answer: A [18 groups, 7 periods]
Notes:
The Modern Periodic Table has 18 vertical columns known as ‘groups’ and 7 horizontal rows known as ‘periods’.
14. What do we call the amount of energy required to break one mole of bonds of a particular type between two atoms in a gaseous state?
[A] Ionisation Potential
[B] Bond Enthalpy
[C] Electron affinity
[D] Bond order
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Correct Answer: B [Bond Enthalpy]
Notes:
Bond Enthalpy is the amount of energy required to break one mole of bonds of a particular type between two atoms in a gaseous state. Its unit is KJ-1.
15. Where does the oxidation takes place in a Galvanic cell?
[A] Anode
[B] Cathode
[C] Oxidation does not take place
[D] None of the above
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Correct Answer: A [Anode]
Notes:
In a galvanic cell, the half-cell in which oxidation takes place is called anode and it has a negative potential with respect to the solution. The other half-cell in which reduction takes place is called cathode and it has a positive potential with respect to the solution.
16. Which of the following factors affect the electronic conductance of an electrolytic solution?
[A] the nature of the electrolyte added
[B] size of the ions produced and their solvation
[C] the nature of the solvent and its viscosity
[D] All of the above
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Correct Answer: D [All of the above]
Notes:
The conductance of electricity by ions present in the solutions is called electrolytic or ionic conductance. The conductivity of electrolytic (ionic) solutions depends on: (i) the nature of the electrolyte added (ii) size of the ions produced and their solvation (iii) the nature of the solvent and its viscosity (iv) concentration of the electrolyte (v) temperature (it increases with the increase of temperature).
17. What is the bond length in C=C bond?
[A] 1.00 angstroms
[B] 1.11 angstroms
[C] 1.34 angstroms
[D] 1.55 angstroms
Show Answer
Correct Answer: C [1.34 angstroms]
Notes:
The bond length of a carbon-carbon (C=C) bond is typically around 1.34 angstroms. The bond length is the distance between the two atoms that are bonded together, and it is an important measure of the strength and stability of the bond. In a C=C bond, the bond length is determined by the distance between the nuclei of the two carbon atoms. This distance is determined by the size of the carbon atoms and the number and arrangement of the electrons in the bond. The bond length of a C=C bond is relatively short, which makes it a strong and stable bond.
18. Which of the following is a polymer of amino acids?
[A] Starch
[B] Cellulose
[C] Proteins
[D] None of the above
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Correct Answer: C [Proteins]
Notes:
Proteins are the polymers of amino acids. They have generally 20 to 1000 amino acids joined together in a highly organized arrangement.
19. Which of the following metals can easily be cut with a knife?
[A] Sodium
[B] Manganese
[C] Zinc
[D] Tin
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Correct Answer: A [Sodium]
Notes:
Out of all the given options, Sodium is a softer metal and can be easily cut with a knife. It is a highly reactive metal which is silvery white in colour.
20. Which of the following metals is involved in the anodisation process?
[A] Aluminium
[B] Copper
[C] Bismuth
[D] Calcium
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Correct Answer: A [Aluminium]
Notes:
Anodising is a process of forming a thick oxide layer of aluminium. Aluminium develops a thin oxide layer when exposed to air. This layer of aluminium oxide makes aluminium resistant to further corrosion.
