Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
11. What are the constituents of German Silver alloy?
[A] Gold, Aluminium and Copper
[B] Zinc, iron and Silver
[C] Bismuth, Antimony and Tin
[D] Copper, Nickel and Zinc
Show Answer
Correct Answer: D [Copper, Nickel and Zinc]
Notes:
German silver is a copper alloy with nickel and zinc. It is also known as Nickel silver or Maillechort. The usual composition is 60% copper, 20% nickel and 20% zinc.
12. Which of the following is / are correct statement(s) about Gypsum?
[A] It’s a mineral composed of calcium sulfate dihydrate
[B] It is a soft mineral
[C] It is commonly added to saline soils to reduce salinity
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Gypsum is a mineral composed of calcium sulfate dihydrate. It’s a soft mineral and colorless to white in color. It is commonly added to saline soils to reduce salinity and also used in wallboard (drywall) and plaster of paris.
13. What is Zeeman effect?
[A] splitting of spectral line in presence of magnetic field
[B] splitting of spectral line in presence of electric field
[C] convergence of spectral line in presence of magnetic field
[D] convergence of spectral line in presence of electric field
Show Answer
Correct Answer: A [splitting of spectral line in presence of magnetic field]
Notes:
Zeeman effect refers to the splitting of a spectrum line into several components by the application of a magnetic field. It is named after the Dutch physicist Pieter Zeeman.
14. What do we call the difference between the initial mass energy and the total mass energy of the decay products in a radioactive decay?
[A] entropy
[B] disintegration energy
[C] alpha energy
[D] integration energy
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Correct Answer: B [disintegration energy]
Notes:
The disintegration energy or the Q-value of a nuclear reaction is the difference between the initial mass energy and the total mass energy of the decay products.
15. 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
Show Answer
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).
16. The cell constant does not depend on which of the following?
[A] distance between the electrodes
[B] area of cross-section of electrodes
[C] nature of electrolyte
[D] None of the above
Show Answer
Correct Answer: C [nature of electrolyte]
Notes:
The cell constant depends on the distance between the electrodes and their area of cross-section. It has the dimension of length-1.
17. What do we call the molar conductivity when the concentration approaches zero?
[A] Reacting molar conductivity
[B] Zero level molar conductivity
[C] Limiting molar conductivity
[D] Ideal molar conductivity
Show Answer
Correct Answer: C [Limiting molar conductivity]
Notes:
When concentration approaches zero, the molar conductivity is known as limiting molar conductivity.
18. Which of these laws state that limiting molar conductivity of an electrolyte can be represented as the sum of the individual contributions of the anion and cation of the electrolyte?
[A] Nernst Equation
[B] Kohlrausch law
[C] Afbau Principle
[D] Faraday’s law of electrolyte
Show Answer
Correct Answer: B [Kohlrausch law]
Notes:
Kohlrausch law of independent migration of ions states that limiting molar conductivity of an electrolyte can be represented as the sum of the individual contributions of the anion and cation of the electrolyte.
19. Which of the following metals is commonly used to increase the strength of steel alloys?
[A] Bismuth
[B] Boron
[C] Tin
[D] Molybdenum
Show Answer
Correct Answer: D [Molybdenum]
Notes:
Molybdenum is commonly used in steel alloys to increase strength, hardness, electrical conductivity and resistance to corrosion and wear.
20. What is the colour of Rhombic sulphur?
[A] Red
[B] Yellow
[C] Black
[D] Colorless
Show Answer
Correct Answer: B [ Yellow ]
Notes:
Rhombic sulphur is an allotrope of Sulphur which is yellow in colour. Rhombic sulphur crystals are formed on evaporating the solution of roll sulphur. It is also known as alpha-sulphur.
