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 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.
2. In what form is Nitrogen present in Urea?
[A] Nitrite
[B] Nitrate
[C] Ammonium
[D] Amide
Show Answer
Correct Answer: D [Amide]
Notes:
Urea is an organic compound with the formula (NH2)2CO. The Nitrogen present in Urea is in the form of Amide. This compound is highly soluble in water and is a very effective source of Nitrogen for plants. It is the main nitrogenous end product of the metabolic breakdown of proteins in all mammals and some fishes.
3. Which of the following statements about the chemical nature of Diamond and Graphite is incorrect?
[A] The density of Diamond is greater than that of Graphite
[B] Diamond is chemically unreactive whereas Graphite mildly reacts with certain elements
[C] Both Diamond and Graphite are excellent conductors of electricity
[D] None of the above statements is incorrect
Show Answer
Correct Answer: C [Both Diamond and Graphite are excellent conductors of electricity]
Notes:
Diamond and graphite are both forms of carbon but they exhibit different properties due to variations in their bonding arrangements. Diamond does not conduct electricity as each carbon atom in diamond is covalently bonded to four other carbon atoms, leaving no free electrons to conduct electricity. On the other hand, graphite is a good conductor of electricity due to its layered structure which leaves free electrons between the layers.
4. Which of the following elements is the most electronegative?
[A] Chlorine
[B] Fluorine
[C] Bromine
[D] All of them have the same electronegativity
Show Answer
Correct Answer: B [Fluorine]
Notes:
Electronegativity is defined as an atom’s ability to attract an electron pair when forming a covalent bond. This property increases as you move left to right across the periodic table due to an increase in the nuclear charge’s attractive forces. It decreases as you move top to bottom, owing to the shielding effect of sub-levels and increased atomic radius, which makes electrons easier to remove. This culminates in Fluorine, being the highest and furthest to the right on the periodic table, hence it is the most electronegative.
5. Which among the following alkane has largely replaced the ozone layer-depleting halomethanes in household refrigerators and freezers?
[A] Methane
[B] Propane
[C] Butane
[D] Ethane
Show Answer
Correct Answer: C [Butane]
Notes:
Isobutane, which is known in the industry as R600A has been used in several domestic refrigerators in recent times because it is an excellent refrigerant and non-ozone depleting substance with low global warming potential. The only drawback is that it is highly inflammable.
6. L.P.G. is a hydrocarbon consisting of a mixture of :
[A] Methane and Butane
[B] Propane and Butane
[C] Ethane and Propane
[D] Ethane and Butane
Show Answer
Correct Answer: B [Propane and Butane]
Notes:
L.P.G. (Liquefied Petroleum Gas) primarily consists of propane and butane. It is used as fuel for heating, cooking, and vehicles. Propane (C3H8) and butane (C4H10) are both byproducts of natural gas processing and petroleum refining. LPG is favored for its high energy content and clean-burning properties.
7. Which of the following is the most common naturally occurring form in which silicon is found?
[A] Oxide
[B] Fluoride
[C] Nitride
[D] Sulphide
Show Answer
Correct Answer: A [ Oxide ]
Notes:
Silica is also known as Silicon dioxide, is the most prevalent form of naturally occurring silicon.
8. Plumbism is a condition which occurs due to accumulation of:
[A] Lead in the body
[B] Sodium in the body
[C] Cadmium in the body
[D] Potassium in the body
Show Answer
Correct Answer: A [ Lead in the body]
Notes:
Plumbism is also known as lead poisoning or a condition which occurs when there is accumulation of lead in body, usually over a few months' time period and even years.
9. What happens to the non-metallic character of elements in the p-block of the periodic table?
[A] non-metallic character decreases down the group
[B] non-metallic character increases down the group
[C] No fix pattern
[D] None
Show Answer
Correct Answer: A [non-metallic character decreases down the group]
Notes:
The non-metallic character of elements decreases down the group. In fact, the heaviest element in each p-block group is the most metallic in nature.
10. Which of the following alkaline earth metals is the rarest in the earth crust?
[A] Calcium
[B] Strontium
[C] Radium
[D] Beryllium
Show Answer
Correct Answer: C [Radium]
Notes:
Of the alkaline earth metals calcium and magnesium rank fifth and sixth in abundance respectively in the earth’s crust. Strontium and barium have much lower abundances. Beryllium is rare and radium is the rarest of all comprising only 10–10 per cent of igneous rocks.
