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 are the most and the least electronegative elements in the periodic table?
[A] Fluorine and Caesium
[B] Hydrogen and Helium
[C] Carbon and Oxygen
[D] Chlorine and Fluorine
Show Answer
Correct Answer: A [Fluorine and Caesium]
Notes:
Caesium is the least electronegative element in the periodic table and Fluorine is the most electronegative. Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.
2. Which among the following is the correct set of chemical formulae of Chile Saltpetre, Saltpetre and Quick Lime?
[A] KNO3, NaNO3, CaO
[B] NaNO3, KNO3, Ca(OH)2
[C] Na(OH)2, KOH, CaO
[D] NaNO3, KNO3, CaO
Show Answer
Correct Answer: D [NaNO3, KNO3, CaO]
Notes:
Saltpetre, also spelled Saltpeter, also called Nitre, or Niter, any of three naturally occurring nitrates, distinguished as (1) ordinary saltpetre, or potassium nitrate, KNO3; (2) Chile saltpetre, cubic nitre, or sodium nitrate, NaNO3; and (3) lime saltpetre, wall saltpetre, or calcium nitrate, Ca(NO3)2.
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound.
3. The energy required to remove an electron from the outermost shell of an atom in its isolated gaseous state is called?
[A] Electron Affinity
[B] Reducing Potential
[C] Ionization Potential
[D] Shell Potential
Show Answer
Correct Answer: C [Ionization Potential ]
Notes:
Ionization potential is the energy required to remove an electron from the outermost shell of an atom in its isolated gaseous state. As we move down the group, ionization potential decreases. As we move across the period, ionization potential increases Electron affinity is the energy released on adding an electron to the outermost shell of an atom in its isolated gaseous state.
4. Which among the following are constituents of Brass?
[A] Zinc and Copper
[B] Iron and Zinc
[C] Copper and Nickel
[D] Iron and Copper
Show Answer
Correct Answer: A [Zinc and Copper ]
Notes:
Brass is an alloy of Copper and Zinc, in proportions which can be varied to achieve varying mechanical and electrical properties. The proportions of Zinc and Copper can vary to create different types of brass alloys with varying mechanical and electrical properties.
5. 2,4-D, which is sold as a weed killer of the broad-leaved weeds is a synthetic version of __:
[A] Auxin Hormone
[B] Cytokinin Hormone
[C] Xylitol
[D] None of them
Show Answer
Correct Answer: A [Auxin Hormone ]
Notes:
2,4-dichlorophenoxyacetic acid (2,4-dichlorophenoxyethanoic acid) is a synthetic auxin frequently used as a weed killer of broad-leaved weeds. When two herbicides 2,4,5-T and 2,4-D and mixed in equal parts, it is called Agent Orange, which was used by US in Vietnam war.
6. Which among the following substances is most suitable for making Compact Discs?
[A] PVC
[B] Polyethylene
[C] Polyamides
[D] Polycarbonates
Show Answer
Correct Answer: D [Polycarbonates
]
Notes:
Polycarbonate(PC) is a tough thermoplastic. It is not only highly transparent but also has good toughness which most of the other thermoplastics do not possess. For this reason, it is widely used for making CDs, Safety Goggles, Mixer jar lids etc.
7. A cotton wick dipped in pure honey when ignited with a matchstick will ______?
[A] Burn steadily
[B] Burn with a cracking sound
[C] Not burn at all
[D] Burn producing a large amount of smoke
Show Answer
Correct Answer: A [Burn steadily]
Notes:
A cotton wick soaked in pure honey, when lit with a matchstick, will burn consistently. This is primarily due to the high sugar content of the honey acting as fuel for the flame. Contrary to common misconceptions, honey doesn’t produce much smoke or any unusual sounds during combustion.
8. 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.
9. If a Hydrogen atom is removed from a hydrocarbon of Benzene group, the remaining residue is called _________?
[A] Alkyl
[B] Aryl
[C] Arene
[D] Azene
Show Answer
Correct Answer: B [Aryl]
Notes:
The correct answer is Aryl. In organic chemistry, when a hydrogen atom is removed from a benzene ring (a hydrocarbon), the remaining structure is referred to as an aryl group. Aryl groups are derived from aromatic compounds, specifically those containing a benzene ring. For example, when a hydrogen is removed from toluene (methylbenzene), the resulting aryl group is called a tolyl group. Aryl groups are important in various chemical reactions and are foundational in the synthesis of many organic compounds.
10. If a baby diaper is subjected to different solutions, which of the following will it absorb the maximum quantity of?
[A] Distilled Water
[B] Drinking Water
[C] Hard Water
[D] Urine
Show Answer
Correct Answer: A [Distilled Water]
Notes:
A baby diaper can absorb the maximum quantity of distilled water as it lacks impurities such as minerals and ions that are present in other type of water. The absorbent materials in diapers, often polymers called sodium polyacrylate, can hold up to 30 times their weight in distilled water, making them highly efficient.