Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
41. Which of the following metal (shown by its symbol) is generally used for making filaments of bulb?
[A] Fe
[B] An
[C] Ag
[D] W
Show Answer
Correct Answer: D [W]
Notes:
Tungsten, a chemical element with symbol W, is used in incandescent light bulb filaments, X-ray tubes (as both the filament and target), electrodes in TIG welding, super-alloys, and radiation shielding. It has the highest melting point of all the elements discovered, melting at 3422 °C (6192 °F, 3695 K). It also has the second highest boiling point, at 5930 °C.
42. Which among the following is an incorrect pair?
(Natural source) – (Acid)
- Vinegar – Acetic acid
- Curd – Lactic acid
- Tamarind – Citric acid
Select the correct answer from the codes given below:
[A] Only 1 and 2
[B] Only 2 and 3
[C] Only 2
[D] Only 3
Show Answer
Correct Answer: D [Only 3]
Notes:
Tamarinds contain high levels of tartaric acid, just as citrus fruits contain citric acid. Tartaric acid, a carboxylic acid, gives tamarind its sour color. It also contains a significant level of vitamin C, E, and B, calcium, iron, phosphorous, potassium, manganese, and dietary fiber. There are also a number of organic compounds that make tamarind a powerful antioxidant and anti-inflammatory agent.
43. Which of the following is the symbol of the metal that occurs in liquid form at ordinary temperature?
[A] K
[B] Ag
[C] Pb
[D] Hg
Show Answer
Correct Answer: D [Hg]
Notes:
Mercury is the only metal that is liquid at room temperature. It has the lowest melting point and boiling point of any other metal. It has low thermal conductivity, and a quite low electrical conductivity. It is the only metal that doesn’t form diatomic molecules in the gaseous phase.
44. Which of the following group does not follow Newlands Law of Octaves?
[A] Li, Na
[B] Be, Mg
[C] C, Si
[D] Mn, Hg
Show Answer
Correct Answer: D [Mn, Hg]
Notes:
Law of octaves refer to the generalization made by the English chemist J.A.R. Newlands in 1865 that, if the chemical elements are arranged according to increasing atomic weight, those with similar physical and chemical properties occur after each interval of seven elements. However, Newlands’ law of octaves worked well only with lighter elements and was found to be applicable only upto calcium. Both Mercury (Hg) and Manganese (Mn) do not follow this law.
45. What is the chemical name of quick lime?
[A] Calcium carbonate
[B] Sodium hydroxide
[C] Calcium oxide
[D] Calcium sulphate
Show Answer
Correct Answer: C [Calcium oxide]
Notes:Calcium oxide (CaO) is commonly known as quicklime. The raw material used for the manufacture of quicklime is calcium carbonate (CaCO3). Lime is manufactured by heating the calcium carbonate to a temperature of 1273K in a lime kiln.
- CaCO3 (Lime stone) —> CaO (Lime) + CO2 (Carbon dioxide)
46. Washing soda is used:
- for removing permanent hardness of water
- for disinfecting drinking water
- as a cleaning agent for domestic purpose
Which of the above is / are correct?
[A] Only 1 and 2
[B] Only 1 and 3
[C] Only 2 and 3
[D] All of the above
Show Answer
Correct Answer: B [Only 1 and 3]
Notes:
Sodium carbonate (Na2CO3), also known as washing soda or soda ash, is used as a water softener in laundering. It competes with the magnesium and calcium ions in hard water and prevents them from bonding with the detergent being used. Sodium carbonate can be used to remove grease, oil, and wine stains. It is also used for removing the permanent hardness of water.
47. Bayer’s reagent is:
[A] Alkaline potassium permanganate
[B] Acidified potassium permanganate
[C] Hydrogen peroxide
[D] Bromine water
Show Answer
Correct Answer: A [Alkaline potassium permanganate]
Notes:
Baeyer’s reagent is an alkaline solution of potassium permanganate, which is a powerful oxidant. It is used in organic chemistry in a qualitative test for finding the presence of unsaturation. i.e. presence or absence of double or triple bond in hydrocarbon.
48. Citric acid is present in free form in:
[A] Tamarind
[B] Milk
[C] Apple
[D] Lemon
Show Answer
Correct Answer: D [Lemon]
Notes:
Lemons, oranges, limes, and other citrus fruits naturally possess high concentrations of citric acid. The juice of the lemon is about 5% to 6% citric acid, which gives lemons a sour taste. Raw Amala is the richest source of citric acid among all citrus fruits.
49. Which substance is produced when alcohol is added with petrol and used as a fuel?
[A] Only oxygen
[B] Only carbondioxide
[C] Only water
[D] Carbon-dioxide and water both
Show Answer
Correct Answer: B [Only carbondioxide]
Notes:When alcohol (methanol, ethanol, propanol, and butanol) is mixed with petrol and used as a fuel, it produces carbon dioxide. Adding alcohol enhances the octane contents in the fuel and hence acts as anti-knocking agent.
- Butanol combustion : C4H9OH + 6O2 —> 4CO2 + 5H2O + heat
- Propanol combustion : 2C3H7OH + 9O2 —> 6CO2 + 8H2O + heat
50. Depleted uranium, a by-product of uranium enrichment can be used:
[A] Fuel for nuclear reactors
[B] To treat cancer
[C] In military weapons
[D] None of the above
Show Answer
Correct Answer: C [In military weapons]
Notes:- Depleted uranium (DU) is a by-product of uranium enrichment.
- Enriched uranium is highly radioactive and is used in nuclear reactors and nuclear weapons.
- In comparison to enriched uranium, depleted uranium is much less radioactive and is incapable of generating a nuclear reaction.
- Due to its high density (more dense than lead), depleted uranium is widely used in weapons as it can easily penetrate armour plating.
- The US began manufacturing armour-piercing rounds with depleted uranium in the 1970s and has since added it to composite tank armour to strengthen it.
These questions are part of GKToday's 40,000+ GK Questions Course in GKToday Android Application which provides more than 40K questions with explanations suitable for all Competitive Exams of India.
Advertisement 
