General Science Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination. These questions are part of GKToday’s 35000+ MCQs Bank Course in GKToday Android App
41. Which of the following has least melting point?
[A] Carbon
[B] Silver
[C] Mercury
[D] Gold
Show Answer
Correct Answer: C [Mercury]
Notes:
Among the given options, mercury has the lowest melting point of -38.83 °C. in fact, Mercury has the lowest melting point among all metals and is the only metal that exists as liquid at room temperature. The melting point of Carbon, Silver and Gold is 3550 °C, 961.78 °C and 1064.18 °C respectively.
42. Bauxite is an alloy of which of the following metals?
[A] Aluminium
[B] Silver
[C] Tin
[D] Iron
Show Answer
Correct Answer: A [Aluminium]
Notes:
Bauxite (Al2O3.2H2O) is an aluminium ore and is the main source of aluminium. This form of rock consists mostly of the minerals gibbsite Al(OH)3, boehmite -AlO(OH), and diaspore a-AlO(OH), in a mixture with the two iron oxides goethite and hematite, the clay mineral kaolinite, and small amounts of anatase TiO2. Bauxite was named after the village Les Baux in southern France, where it was first recognised as containing aluminium and later named by the French geologist Pierre Berthier in 1821.
43. An electrochemical cell which is used as a source of direct electrical current at constant voltage under standard conditions is called a:
[A] Power transmitter
[B] Battery
[C] Uninterrupted power supply (UPS)
[D] Generator
Show Answer
Correct Answer: B [Battery]
Notes:
A Galvanic cell, also known as battery, is an electro-chemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell. It is typically used as a source of electrical power. By their nature, they produce direct current. A battery is a set of galvanic cells that are connected in series.
44. What is the chemical formula for Sodium Chloride (Salt)?
[A] NaCl2
[B] NaCl
[C] Na2Cl
[D] Na2C
Show Answer
Correct Answer: B [NaCl]
Notes:
Sodium chloride, also known as salt or halite, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. Sodium chloride is the salt most responsible for the salinity of seawater. In its edible form of table salt, it is commonly used as a condiment and food preservative.
45. Which of the following is slaked lime?
[A] Ca(OH)2
[B] CaO
[C] CaCO3
[D] CaCl2
Show Answer
Correct Answer: A [Ca(OH)2]
Notes:
Calcium hydroxide, traditionally called slaked lime, hydrated lime, slack lime or pickling lime, is a chemical compound with the chemical formula Ca(OH)2. It is a colourless crystal or white powder, and is obtained when calcium oxide (called lime or quicklime) is mixed, or slaked with water.
46. The Refrigerant ‘FREON’ is:
[A] Calcium Tetra Fluoride
[B] Difluoro Dichloro Methane
[C] Fluorspar and Felspar
[D] Hydrofluosilicic Acid
Show Answer
Correct Answer: B [Difluoro Dichloro Methane]
Notes:
Dichlorodifluoromethane (R-12), is a colourless gas, and usually sold under the brand name Freon-12, is a chlorofluorocarbon halomethane (CFC), used as a refrigerant and aerosol spray propellant. Complying with the Montreal Protocol, it is prepared by reacting carbon tetrachloride with hydrogen fluoride in the presence of a catalytic amount of antimony pentachloride. This reaction also produces trichlorofluoromethane (CCl3F), chlorotrifluoromethane (CClF3) and tetrafluoromethane (CF4).
47. Rectified spirit is:
[A] 95% ethyl alcohol
[B] 100% ethyl alcohol
[C] methylated spirit
[D] tincture of iodine
Show Answer
Correct Answer: A [95% ethyl alcohol]
Notes:
Rectified spirit, also known as ethyl alcohol of agricultural origin, is highly concentrated ethanol which has been purified by means of repeated distillation, called rectification. It typically contains 95% ethyl alcohol by volume.
48. What is the water found below water table called?
[A] Water cycle
[B] Water table
[C] Ground water
[D] Aquifer
Show Answer
Correct Answer: C [Ground water]
Notes:
Water table, also called Groundwater Table, upper level of an underground surface in which the soil or rocks are permanently saturated with water. The water table separates the ground water zone that lies below it from the capillary fringe, or zone of aeration, that lies above it.
49. What is the major component of Gobar Gas?
[A] Propane
[B] Butane
[C] Methane
[D] Ethylene
Show Answer
Correct Answer: C [Methane]
Notes:
Gobar Gas is produced by the anaerobic digestion or fermentation of biodegradable materials such as manure, sewage, municipal waste, green waste, plant material, and crops. It comprises primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes.
50. Chemistry of carbon compounds is known is:
[A] biochemistry
[B] physical chemistry
[C] inorganic chemistry
[D] organic chemistry
Show Answer
Correct Answer: D [organic chemistry]
Notes:
In chemistry, an organic compound is generally any chemical compound that contains carbon. Organic compounds contain carbon bonds in which at least one carbon atom is covalently linked to an atom of another type (usually hydrogen, oxygen or nitrogen). Most polymers are organic compounds.
