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 acids is abundant in Grapes, Bananas and Tamarind?
[A] Lactic Acid
[B] Oxalic Acid
[C] Salicylic Acid
[D] Tartaric Acid
Show Answer
Correct Answer: D [Tartaric Acid ]
Notes:
Tartaric acid occurs naturally in many fruits such as grapes, bananas, tamarinds, and citrus. Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally in the process of winemaking. It is commonly mixed with sodium bicarbonate and is sold as baking powder used as a leavening agent in food preparation. The acid itself is added to foods as an antioxidant E334 and to impart its distinctive sour taste.
2. Galena & Litharge are ores of which of the following metals?
[A] Mercury
[B] Zinc
[C] Copper
[D] Lead
Show Answer
Correct Answer: D [Lead]
Notes:
Galena and litharge are ores of lead. Galena is the most common ore of lead. It is the natural mineral form of lead (II) sulphid. Litharge is a secondary mineral that forms from the oxidation of galena ores. It is one of the natural mineral forms of Lead(II) oxide.
3. Consider the following:
- Cinnabar is also known as mercurblende
- The color of Cinnabar varies from dull grey to bright green
- Cinnabar is the most common source ore for refining elemental mercury
- Cinnabar is the historic source for the brilliant blue pigment termed azure
Which of the statements given above are correct?
[A] Only 1 and 3
[B] Only 2 and 4
[C] 1, 3 and 4
[D] All Four
Show Answer
Correct Answer: A [Only 1 and 3]
Notes:
Cinnabar, also known as mercurblende, is indeed the most common ore source for refining elemental mercury. However, its color range runs from scarlet to brick-red, not grey to green. It is known for providing the brilliant red or scarlet pigment known as vermilion, not a blue pigment.
4. Which among the following can be used as a preservative in Tomato Juice?
[A] Sodium Chloride
[B] Sodium carbonate
[C] Sodium benzoate
[D] Sodium Lauril Sulphate
Show Answer
Correct Answer: C [Sodium benzoate]
Notes:
Sodium benzoate is commonly used as a preservative in food and beverages, including tomato juice. It inhibits the growth of mold, yeast, and some bacteria, extending shelf life. It is effective in acidic environments, such as those found in tomato products, where the pH is typically below 4.6. Sodium chloride (salt) can also act as a preservative but is primarily used for flavor. Sodium carbonate and sodium lauryl sulfate are not suitable preservatives for tomato juice.
5. How does the Isotope of Iodine, Iodine-135 plays an important role in Nuclear Power Generation?
[A] It is used as a fuel supplement in some of the modern Nuclear Reactors
[B] It is a bi-product of Nuclear Reaction which kills the neutrons and this inhibits the power formation
[C] It is a moderator used actively in the Nuclear Reactors
[D] It is an experimental substance for Nuclear Fusion
Show Answer
Correct Answer: B [It is a bi-product of Nuclear Reaction which kills the neutrons and this inhibits the power formation]
Notes:
Iodine-135 is a important by-product of nuclear fission, particularly in reactors using uranium fuel. It has a high neutron capture cross-section, meaning it effectively absorbs neutrons, which can inhibit the fission process and reduce reactor power output. This property makes it crucial for managing reactor control and safety, as its presence can lead to a phenomenon known as “neutron poison,” affecting the overall efficiency of the nuclear reaction.
6. The colors in the fine cut diamond are because of which among the following?
[A] Variance in transparency of diamond
[B] Variance in index of refraction
[C] Presence of Impurities
[D] Existence of definite planer layers
Show Answer
Correct Answer: C [Presence of Impurities]
Notes:
Pure diamond should transmit visible light and appear as a clear colorless crystal. Colors in diamond originate from lattice defects and impurities. The diamond crystal lattice is exceptionally strong and only atoms of nitrogen, boron and hydrogen can be introduced into diamond during the growth at significant concentrations (up to atomic percents). Nitrogen gives yellowish color while the Boron gives bluish color.
7. Which of the following is NOT correct about Ethanol?
[A] It is a good solvent
[B] It gives out hydrogen when reacted with Sodium
[C] It is an odorless liquid
[D] All are correct
Show Answer
Correct Answer: C [It is an odorless liquid]
Notes:
Ethanol is a good solvent and reacts with sodium leading to the evolution of hydrogen. It is a colorless liquid with a slight characteristic odor.
8. Which of the following methods is most suitable for ore concentration if the ore is soluble in some suitable solvent?
[A] Hydraulic Washing
[B] Magnetic Separation
[C] Froath floatation
[D] Leaching
Show Answer
Correct Answer: D [Leaching]
Notes:
Leaching is used for ore concentration if the ore is soluble in some suitable solvent. For example: Leaching of alumina from bauxite using conc. NaOH.
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. Which of the following quantum numbers is not necessary to identify an orbital?
[A] Principal quantum number
[B] Azimuthal quantum number
[C] Magnetic quantum number
[D] Electron Spin quantum number
Show Answer
Correct Answer: D [Electron Spin quantum number]
Notes:
An orbital is identified by the set of 3 quantum numbers: Principal quantum number, Azimuthal quantum number and magnetic quantum number.
