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 of the following is the most active chemically?
[A] Chlorine
[B] Flourine
[C] Lithium
[D] Iodine
Show Answer
Correct Answer: B [Flourine]
Notes:
Fluorine is most active because it has the highest electronegativity.
2. 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
3. Which among the following is correct ?
[A] Oxidation takes place at Cathode and Reduction Takes Place at Anode
[B] Oxidation takes place at Anode and Reduction Takes place at Cathode
[C] Both Oxidation and Reduction takes place at cathode
[D] Both Oxidation and Reduction takes place at Anode
Show Answer
Correct Answer: B [Oxidation takes place at Anode and Reduction Takes place at Cathode]
Notes:
In an electrochemical cell, the half cell where oxidation takes place is known as oxidation half cell and the half cell where reduction takes place is known as reduction half cell. Oxidation takes place at anode which is negatively charged and reduction takes place at cathode which is positively charged.
4. Ekaboron was an element predicted by Mendeleev and he leaved a space for it in his Periodic Table. Later Ekaboron was identified with _____?
[A] Gallium
[B] Scandium
[C] Technitium
[D] Germanium
Show Answer
Correct Answer: B [Scandium]
Notes:
Ekaboron was predicted by Dmitri Mendeleev in 1871, who left a space in his Periodic Table for it. It was later identified as Scandium (element 21) in 1879 by Lars Fredrik Nilson. Scandium shares similar properties with Ekaboron, aligning with Mendeleev’s predictions.
5. What term refers to the minimum temperature at which a combustible substance begins to ignite?
[A] Fireless Temperature
[B] Ignition Temperature
[C] Static Temperature
[D] Optimum Temperature
Show Answer
Correct Answer: B [Ignition Temperature]
Notes:
The term for the minimum temperature necessary to ignite a combustible substance is “Ignition Temperature”. It plays a critical role in fire safety and in the field of thermodynamics. Incorrect handling of substances with low ignition temperatures can lead to hazardous situations like unexpected fires or explosions. Additionally, understanding a material’s ignition temperature helps in proper storage and safe handling to prevent unwanted accidents.
6. The synthetic rubber Buna is obtained from the reaction of an unsaturated hydrocarbon with ___:
[A] Sodium
[B] Magnesium
[C] Potassium
[D] Lithium
Show Answer
Correct Answer: A [Sodium]
Notes:
Buna-S is a synthetic rubber formed by co-polymerization of a mixture of 1:3 butadiene and styrene. It is obtained from Sodium.
7. What is dry ice?
[A] solidified form of Carbon dioxide
[B] frozen heavy water
[C] isotope of Hydrogen
[D] popular name of Benzene
Show Answer
Correct Answer: A [solidified form of Carbon dioxide]
Notes:
Carbon dioxide can be obtained as a solid in the form of dry ice by allowing the liquified CO2 to expand rapidly.
8. Which of the following is NOT correct about Sodium chloride?
[A] It is a covalent compound
[B] It is also known as common salt
[C] It is also used in de-icing of roadways during snowfall
[D] It is used as a food preservative
Show Answer
Correct Answer: A [It is a covalent compound]
Notes:
Sodium chloride (NaCl) is used as a common salt or table salt for domestic purpose and used as a food preservative. It is an ionic compound. It is also used in de-icing of roadways during snowfall.
9. Which of the following is incorrect statement about various ores?
[A] Borax is an ore of Sodium
[B] Dolomite is an ore of Aluminium
[C] The chemical formula of Magnetite is Fe3O4
[D] Flourspar is an ore of Potassium
Show Answer
Correct Answer: D [Flourspar is an ore of Potassium]
Notes:
Fluorite or Fluorspar is an ore of Calcium. It is a mineral composed of calcium fluoride. It belongs to the family of halide minerals.
10. 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
Show Answer
Correct Answer: C [2Al + 3CuCl2 – 2AlCl3 + 3Cu]
Notes:
2Al + 3CuCl2 – 2AlCl3 + 3Cu is the balanced equation of Aluminium + Copper chloride – Aluminium chloride + Copper.
