Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
41. The unique ability of carbon to form bonds with other atoms of carbon is called as:
[A] Ionization
[B] Catenation
[C] Acid ification
[D] None of the above
Show Answer
Correct Answer: B [Catenation]
Notes:
Catenation is the binding of an element to itself through covalent bonds to form chain or ring molecules. Carbon is the most common element that exhibits catenation. It can form long hydrocarbon chains and rings like benzene.
42. Which of the following statement(s) is/are correct?
- Metallic oxides are said to be basic oxides.
- Non-metallic oxides are basic in nature.
- All acids have similar chemical properties.
Select the correct answer from the codes given below:
[A] Only 1 and 3
[B] Only 2 and 3
[C] Only 2
[D] All of the above
Show Answer
Correct Answer: A [Only 1 and 3]
Notes:
Oxides are chemical compounds with one or more oxygen atoms combined with another element. Metal oxides react with water to form basic solutions. All non-metals form covalent oxides withoxygen, which react withwater to form acids or with bases to form salts.
43. Solder is an alloy of which of the following metals?
[A] Lead and mercury
[B] Lead and antimony
[C] Lead and copper
[D] Lead and tin
Show Answer
Correct Answer: D [Lead and tin]
Notes:
Solder is a fusible metal alloy used to create a permanent bond between metal workpieces, usually for connections in electrical wiring and in plumbing. Solder is an alloy of lead (70%) and tin (30%).
44. What is the chemical symbol of ‘Iron’?
[A] Ir
[B] Fe
[C] F
[D] In
Show Answer
Correct Answer: B [Fe]
Notes:
Iron is a chemical element with symbol Fe (from Latin: ferrum) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth’s outer and inner core.
45. Raw materials used for the manufacture of glass are:
[A] sand, soda, limestone
[B] sand, charcoal, soda
[C] limestone, charcoal, sulphur
[D] sand, sulphur, soda
Show Answer
Correct Answer: A [sand, soda, limestone]
Notes:
Quartz sand (silica), lime (calcium oxide) along with magnesium oxide (MgO) and aluminium oxide (Al2O3) are used to produce good quality glass. The glass containing about 70 to 74% silica by weight and is called a soda-lime glass. It accounts for about 90% of manufactured glass.
46. Photo chemical smog is a resultant of the reaction among:
[A] High concentration of NO2, O3, and CO in the evening
[B] CO, CO2 and NO2 at low temperature.
[C] CO, O2 and peroxy acetyl nitrate in the presence of Sunlight
[D] NO2, O3 and peroxy acetyl nitrate in the presence of Sunlight
Show Answer
Correct Answer: D [NO2, O3 and peroxy acetyl nitrate in the presence of Sunlight]
Notes:Photochemical smog is a unique type of air pollution which is caused by reactions between sunlight and pollutants like hydrocarbons and nitrogen dioxide (NO and NO2). Other components of the photo-chemical smog include Ozone (O3) formaldehyde, per-oxy benzoyl nitrate (PBzN), peroxy acetyl nitrate (PAN) and acrolein. The formation of photochemical smog can be expressed in the simple terms as:
- Hydrocarbons + NOX + sunlight.
47. ‘Oil of vitriol’ is the common name of which of the following?
[A] Nitric Acid
[B] Carbonic Acid
[C] Acetic Acid
[D] Sulphuric Acid
Show Answer
Correct Answer: D [Sulphuric Acid]
Notes:
Sulfuric acid (H2SO4) was called “oil of vitriol” by medieval European alchemists because it was prepared by roasting “green vitriol” in an iron retort. The acid is oily viscous in nature in its concentrated form and so it derives the name.
48. Why is water not suitable for putting out a petrol fire?
[A] The oxygen content of water is isolated by petrol and thus it helps in burning
[B] Petrol is too inflammable to be extinguished by water
[C] The heat required for combustion of petrol is very low
[D] Water, being heavy, slips below petrol which thus remains in contact with air and burns
Show Answer
Correct Answer: D [Water, being heavy, slips below petrol which thus remains in contact with air and burns]
Notes:
Water is not effective on petrol fire because it has higher density than petrol as a result of which it sinks to the bottom, while petrol stays afloat and keeps burning. Petrochemical fires are always extinguished with chemical foam which forms a in combustible blanket over the flames and cuts off the oxygen supply.
49. In organic compounds, nitrogen is estimated by:
[A] Carius method
[B] Victor-Meyer’s method
[C] Liebig’s method
[D] Dumas’ method
Show Answer
Correct Answer: D [Dumas’ method]
Notes:
In Dumas’ method, a known quantity of nitrogen containing organic compound is heated strongly with excess of copper oxide in an atmosphere of carbon dioxide to produce free nitrogen in addition to carbon dioxide and water.
50. Ethanol containing 5% water is known as:
[A] Dilute alcohol
[B] Power alcohol
[C] Rectified spirit
[D] Absolute alcohol
Show Answer
Correct Answer: C [Rectified spirit]
Notes:
A rectified alcohol is highly concentrated ethanol which has been purified by means of repeated distillation, a process that is called rectification. It typically contains 95% alcohol by volume and 5% water. Normally, ethanol with 5% water is known as pure alcohol.
