Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. When Sulphur is heated with rubber, the process is commonly known as ?
[A] Galvanization
[B] Sulphonation
[C] Vulcanization
[D] Hydrodesulfurization
Show Answer
Correct Answer: C [Vulcanization]
Notes:
Natural rubber becomes soft at high temperature (>335 K) and brittle at low temperatures (<283 k) and shows high water absorption capacity. It is soluble in non-polar solvents and is non-resistant to attack by oxidising agents. To improve upon these physical properties, a process of vulcanisation is carried out. This process consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between 373 K to 415 K. On vulcanisation, sulphur forms cross links at the reactive sites of double bonds and thus the rubber gets stiffened.
In the manufacture of tyre rubber, 5% of sulphur is used as a crosslinking agent
2. Which among the following groups is characteristic to alcohols?
[A] OH group
[B] COOH group
[C] COO group
[D] CO group
Show Answer
Correct Answer: A [OH group]
Notes:
Alcohols are organic compounds characterized by the presence of a hydroxyl group, denoted as -OH. This group consists of one oxygen atom bonded to a hydrogen atom. Due to the presence of the hydroxyl group, alcohols exhibit unique properties, such as the ability to form hydrogen bonds, making them polar. Alcohols are distinct from carboxylic acids (COOH), carbonates (COO), and carbonyl group compounds (CO).
3. Which among the following is correct regarding the alkaline battery ?
[A] Negative terminal made of Zinc Powder and Positive terminal made of Manganese dioxide & electrolyte is KOH
[B] Negative terminal made of Manganese dioxide and Positive terminal made of Zinc powder & electrolyte KOH
[C] Negative terminal made of Zinc Powder and Positive terminal made of Manganese dioxide & Electrolyte is Ammonium Chloride
[D] Negative terminal made of Manganese dioxide and Positive terminal made of Zinc powder & electrolyte Ammonium Chloride
Show Answer
Correct Answer: A [Negative terminal made of Zinc Powder and Positive terminal made of Manganese dioxide & electrolyte is KOH]
Notes:
The correct statement is that in an alkaline battery, the negative terminal is made of zinc powder, the positive terminal is made of manganese dioxide, and the electrolyte is potassium hydroxide (KOH). Alkaline batteries are known for their long shelf life and higher energy density compared to zinc-carbon batteries. They were invented in the 1950s and are widely used in household devices.
4. 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.
5. Which of the following equation represents combination of Hydrogen gas with nitrogen to form ammonia?
[A] 2H2 + N –> NH3
[B] 2H + N3 –> NH3
[C] 3H2 + N2 –> 2NH3
[D] None of the above
Show Answer
Correct Answer: C [3H2 + N2 –> 2NH3]
Notes:
3H2 + N2 –> 2NH3 is the balance equation which represents combination of Hydrogen gas with nitrogen to form ammonia.
6. What do we call the reaction when an acid and a base react together to form salt and water?
[A] Reduction Reaction
[B] Oxidation Reaction
[C] Neutralisation Reaction
[D] Combination Reaction
Show Answer
Correct Answer: C [Neutralisation Reaction]
Notes:
When an acid and a base react together to form salt and water, the reaction is known as Neutralisation Reaction. HCl (aq) + NaOH (aq) ? H2O (l) + NaCl (aq) (acid) (base) (Water) (Salt) Hydrochloric acid Sodium hydroxide Sodium Chloride
7. What do we call the covalent bond where the electrons of the shared pair are contributed by only one species?
[A] Polar Covalent bonds
[B] Coordination Covalent bonds
[C] Unilateral Covalent bonds
[D] None of the above
Show Answer
Correct Answer: B [Coordination Covalent bonds]
Notes:
The covalent bond where the electrons of the shared pair are contributed by only one species are called as Coordination Covalent bonds or Dative bonds. The common example is the formation of a bond between boron trifluoride (BF3) and ammonia (NH3).
8. What do we call the device which converts the chemical energy of a spontaneous redox reaction into electrical energy?
[A] Galvanic cell
[B] Fuel cell
[C] Electrolytic cell
[D] None of the above
Show Answer
Correct Answer: A [Galvanic cell]
Notes:
A galvanic cell is an electrochemical cell that converts the chemical energy of a spontaneous redox reaction into electrical energy. Daniel cell is a kind of Galvanic cell.
9. What is the effect of increase in concentration on the Molar conductivity?
[A] It increases
[B] It decreases
[C] It remains constant
[D] None of the above
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Correct Answer: B [It decreases]
Notes:
Molar conductivity increases with decrease in concentration and decreases with increase in concentration. This is because the total volume of solution containing one mole of electrolyte also increases as the concentration decreases.
10. 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.
