Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. Highest percentage of nitrogen is found in which among the following fertilizers among the given options?
[A] Calcium ammonium nitrate
[B] Ammonium nitrate
[C] Calcium nitrate
[D] Urea
Show Answer
Correct Answer: D [Urea]
Notes:
The agricultural industry widely uses urea, a white crystalline solid containing 46 percent nitrogen as an animal feed additive and fertilizer. Urea has the highest nitrogen content of all solid fertilizers at 46% N.
2. Which among the following types of glasses contains Cerium and other rare earths and has a high absorption of ultraviolet rays?
[A] Crookes Glass
[B] Pyrex Glass
[C] Flint Glass
[D] Crown Glass
Show Answer
Correct Answer: A [Crookes Glass]
Notes:
Crookes glass comprises Cerium oxide (CiO2) which sharply absorbs the ultraviolet rays from the sunlight. It is used in making lenses of eye glasses.
3. PVC is a polymer of__?
[A] Propane
[B] Vinyl chloride
[C] Styrene
[D] Carbonates
Show Answer
Correct Answer: B [Vinyl chloride]
Notes:
Polyvinyl chloride (PVC) is made from the monomer vinyl chloride (CH2 =CHCl). It is used for making raincoats, handbags, toys including dolls, electrical goods and as a covering of electrical wires.
4. Calcium Magnesium Silicate is commonly called as ________?
[A] Asbestos
[B] Borax
[C] Baking Soda
[D] Washing Soda
Show Answer
Correct Answer: A [Asbestos]
Notes:
CaMgO4Si is the chemical formula of calcium magnesium silicate . Calcium magnesium silicate is commonly known as Asbestos. Asbestos is a fibrous silicate mineral as the substance is formed by miniature crystal fibers, these crystal are loosely attached releasing dust of silicate crystal upon small touch.
5. 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.
6. An Jewellery was left exposed to the atmosphere for some time and it becomes coated with green carbonate. The Jewellery is made up of which of the following?
[A] Copper
[B] Silver
[C] Zinc
[D] Gold
Show Answer
Correct Answer: A [Copper]
Notes:
The correct answer is Copper. When copper jewelry is exposed to air and moisture, it reacts with carbon dioxide and water, forming copper carbonate, which appears as a green patina (often called verdigris). This process is known as oxidation. Unlike copper, silver and gold do not typically form green coatings. silver may tarnish to a black color due to silver sulfide formation, while gold is highly resistant to corrosion and tarnishing.
7. Steel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.1% by weight. An increasing amount of Iron will result in which of the following?
[A] Increase Hardening
[B] Decrease Hardening
[C] Increase ductility
[D] Increase melting Point
Show Answer
Correct Answer: A [Increase Hardening]
Notes:
Increasing the amount of iron in steel generally leads to increased hardening. This is due to the formation of a solid solution where carbon atoms occupy interstitial spaces in the iron lattice, enhancing strength and hardness. Steel’s carbon content is crucial. higher carbon levels (up to 2.1%) improve hardness but reduce ductility. The melting point of steel is also influenced by its composition, but the primary effect of increasing iron is hardening.
8. Which among the following gas is used in Balloons?
[A] Hydrogen
[B] Helium
[C] Nitrogen
[D] Oxygen
Show Answer
Correct Answer: B [Helium]
Notes:
The correct answer is Helium. Helium is a non-flammable, lighter-than-air gas, making it safe for use in balloons. Unlike hydrogen, which is highly flammable and poses explosion risks, helium is inert and does not react with other substances. Helium is the second most abundant element in the universe, primarily produced through nuclear fusion in stars. It was first discovered in the sun before being found on Earth.
9. Buckeyballs are basically the allotropes of _________?
[A] Carbon
[B] Sulfur
[C] Phosphorus
[D] Calcium
Show Answer
Correct Answer: A [Carbon]
Notes:
Buckeyballs, or fullerenes, are allotropes of carbon. Discovered in 1985, they consist of 60 carbon atoms arranged in a spherical shape, resembling a soccer ball. This unique structure contributes to their remarkable properties, including high strength and electrical conductivity. Fullerenes are part of a broader class of carbon allotropes, which also includes graphite and diamond.
10. Ekaboron was an element predicted by Mendeleev and he leaved a space for it in his Periodic Table. Later Ekaboron was identified with _____?
[A] Gallium
[B] Scandium
[C] Technitium
[D] Germanium
Show Answer
Correct Answer: B [Scandium]
Notes:
Ekaboron was predicted by Dmitri Mendeleev in 1871, who left a space in his Periodic Table for it. It was later identified as Scandium (element 21) in 1879 by Lars Fredrik Nilson. Scandium shares similar properties with Ekaboron, aligning with Mendeleev’s predictions.
