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 compound is most commonly used in the Photochromic lenses?
[A] Potassium Dichromate
[B] Silver Chloride
[C] Potassium ferrate
[D] Ferric Chloride
Show Answer
Correct Answer: B [Silver Chloride]
Notes:
Photochromatic or Photochromic glass acquires a darker shade when exposed to bright light and returns to its original lighter shade in dim light. This happens because silver halides (iodide or chloride) is added to this glass
2. Potassium permanganate is used to purify water. Which among the following properties of Potassium permanganate helps in this work?
[A] sterilizing
[B] oxidizing
[C] reducing
[D] leaching
Show Answer
Correct Answer: B [oxidizing]
Notes:
Potassium permanganate is a point-of-entry treatment method that oxidizes dissolved iron, manganese, and hydrogen sulfide into solid particles that are filtered out of the water. It can also be used to control iron bacteria growth in wells.
3. What is the common name of Calcium Sulphate Hemihydrate?
[A] Bleaching powder
[B] Slaked lime
[C] Plaster of paris
[D] Detergent
Show Answer
Correct Answer: C [Plaster of paris]
Notes:
Plaster of Paris is calcium sulphate hemihydrate. The formula is given as, CaSO4.1/2 H2O or (2 CaSO4) . H2O. The powder is called plaster of Paris, because the gypsum which was used to get the powder was mainly found in Paris.
4. 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.
5. 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.
6. 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.
7. Which among the following compound is most commonly used in the Photochromic lenses?
[A] Potassium Dichromate
[B] Silver Chloride
[C] Potassium ferrate
[D] Ferric Chloride
Show Answer
Correct Answer: B [ Silver Chloride]
Notes:
Silver halides and most commonly silver Chloride is used in Photochromic lens. But for plastic photochromic lenses, some organic products such as oxazines and naphthopyrans are used.
8. Which of the following is not a metalloid?
[A] Boron
[B] Silicon
[C] Germanium
[D] Titanium
Show Answer
Correct Answer: D [ Titanium]
Notes:
The most commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. The other less recognised metalloids are: carbon, aluminium, selenium, polonium and astatine.Titanium is a lustrous transition metal with a silver color, low density and high strength.
9. Which of the following catalyst is used generally during the hydrogenation of Alkenes?
[A] Platinum
[B] Palladium
[C] Nickel
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Dihydrogen gas adds to alkenes and alkynes in the presence of finely divided catalysts like platinum, palladium or nickel to form alkanes.
10. Which of the following is correct about suspension?
[A] It is a heterogeneous mixture
[B] The particles of a suspension can be seen by naked eyes
[C] The particles can be separated from the mixture by the process of filtration
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Suspension is a heterogeneous mixture. The particles of a suspension can be seen by the naked eye. The solute particles can be separated from the mixture by the process of filtration.
