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 not a correct statement about Bitumen?
[A] It’s a mixture of highly condensed polycyclic aromatic compounds
[B] Its is soluble in Carbon Disulphide
[C] SARA analysis is used to determine bitumen chemistry
[D] All of above are correct statements
Show Answer
Correct Answer: D [ All of above are correct statements ]
Notes:
Bitumen is a mixture of organic liquids that are highly viscous, black, sticky, soluble in carbon disulfide and composed of highly condensed polycyclic aromatic hydrocarbons.
2. Which among the following is a common salt in Detergents?
[A] Sulphate
[B] Nitrate
[C] Sulphonate
[D] Carbonate
Show Answer
Correct Answer: A [Sulphate]
Notes:
Sodium sulfate, used as a filler in detergent powder, enables the adjustment of the concentration of the active matter in the detergent, as required.
3. What is Carbamide?
[A] A Pesticide
[B] A Fertilizer
[C] A Textile Dye
[D] An Explosive
Show Answer
Correct Answer: B [A Fertilizer]
Notes:
Carbamide is another name of Urea, an organic compound with chemical formula CO(NH2)2. This name indicates that Urea is an amide in which two –NH2 groups are joined by a carbonyl (C=O) functional group.
4. Normal” rainfall is slightly acidic (and a pH of 5.6 has been assigned which might be somewhere near 5 ) because of the presence of _______?
[A] Nitric Oxide
[B] Sulphuric Acid
[C] Nitric Acid
[D] Carbonic Acid
Show Answer
Correct Answer: D [Carbonic Acid]
Notes:
Normal rainfall is slightly acidic due to the presence of carbonic acid, which forms when carbon dioxide (CO2) dissolves in water. The pH of normal rainwater is typically around 5.6, making it mildly acidic. This natural acidity is a result of the CO2 in the atmosphere, which is produced by respiration, combustion, and other natural processes.
5. With reference to the Radioactivity, which among the following is called an isomeric transition?
[A] Alpha emission
[B] Gamma emission
[C] Beta emission
[D] X-Ray emission
Show Answer
Correct Answer: B [ Gamma emission]
Notes:
An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer. The emission of a gamma ray from an excited nuclear state allows the nucleus to lose energy and reach either a lower energy state, sometimes its ground state. In certain cases, the excited nuclear state following a nuclear reaction or other type of radioactive decay, has a half live that is more than 100 to 1000 times longer than the average 10-12 seconds, and this excited state is referred to as a metastable nuclear excited state. Some nuclei are able to stay in this metastable excited state for minutes, hours, days, or occasionally far longer, before undergoing gamma decay, in which they undergo radioactive decay with primary emission of a gamma ray.
6. What do we call the energy required to remove loosely bound electron from an atom?
[A] Excitation energy
[B] Atom energy
[C] Ionization energy
[D] Shell energy
Show Answer
Correct Answer: C [Ionization energy]
Notes:
Ionization energy is the quantity of energy required to remove loosely bound electron from an atom.
7. What is the general trend for ionization enthalpies of alkali metals as we move down the group?
[A] it increases
[B] it decreases
[C] it is same for all
[D] None
Show Answer
Correct Answer: B [it decreases]
Notes:
The ionization enthalpies of the alkali metals are considerably low and decrease down the group from Li to Cs.
8. Which of the following is correct about Ammonia?
[A] The ammonia molecule is trigonal pyramidal in shape
[B] Ammonia gas is light blue in colour
[C] its aqueous solution is highly basic
[D] Ammonia gas is odorless
Show Answer
Correct Answer: A [The ammonia molecule is trigonal pyramidal in shape]
Notes:
Ammonia is a colourless gas with a pungent odour. Its aqueous solution is weakly basic due to the formation of OH– ions. The ammonia molecule is trigonal pyramidal in shape.
9. What do we call the process of converting an ore into its oxide by heating it in a limited supply of air below its melting point?
[A] Roasting
[B] Calcination
[C] Leaching
[D] Liquation
Show Answer
Correct Answer: B [Calcination]
Notes:
Calcination is the process of converting an ore into its oxide by heating it in a limited supply of air or in absence of air, below its melting point. It is used to convert the concentrated ore to its oxide.
10. Galena is an ore of which of the following metals?
[A] Tin
[B] Copper
[C] Lead
[D] Gold
Show Answer
Correct Answer: C [Lead]
Notes:
Galena is an ore of Lead. It is also known as lead glance. It is the natural mineral form of lead sulfide (PbS).