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 is known as White Vitriol?
[A] Zinc Sulphate
[B] Zinc Chloride
[C] Zinc Phosphate
[D] Zinc oxide
Show Answer
Correct Answer: A [Zinc Sulphate]
Notes:
Zinc sulfate is the inorganic compound with the formula ZnSO4 and historically known as “white vitriol” Zinc sulfate is an inorganic compound and dietary supplement.
2. Trimethylxanthine is a chemical name of a stimulant which is found in tea and coffee. What is the popular name?
[A] Thein
[B] Caffeine
[C] Theobromine
[D] Theophylline
Show Answer
Correct Answer: B [Caffeine]
Notes:
Caffeine (1, 3, 7-trimethylxanthine) also known as ancient wonder drug is a basically a neurostimulant easily available all over the world and is used in different products like tea, coffee, analgesic adjuvant, soft drinks and many dietary supplements.
3. The atomic weight of Chlorine is 35. It consists of _______?
[A] 17 Protons + 18 Neutrons
[B] 17 Neutrons + 18 protons
[C] 17 Neutrons + 17 Protons + 1 electron
[D] None of the above
Show Answer
Correct Answer: A [17 Protons + 18 Neutrons]
Notes:
Chlorine has an atomic number of 17, meaning it has 17 protons. Its atomic weight is approximately 35, which indicates it typically has 18 neutrons (35 – 17 = 18). Therefore, the correct composition is 17 protons and 18 neutrons. Chlorine is a halogen and exists primarily as two stable isotopes: Chlorine-35 and Chlorine-37.
4. 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.
5. Sodium bicarbonate decomposes above 70 °C, making it usable in bakery products. What end product of this thermal decomposition process contributes to its use in baking?
[A] Hydrogen
[B] Carbon Dioxide
[C] Water Vapor
[D] Sodium Carbonate
Show Answer
Correct Answer: B [Carbon Dioxide]
Notes:
Sodium bicarbonate, commonly known as baking soda, is used in baking due to its ability to decompose above 70 degrees Celsius and release carbon dioxide. This chemical reaction is given by the equation 2 NaHCO3 – Na2CO3 + H2O + CO2. In baking, it reacts with other ingredients or decomposes at high temperatures to produce carbon dioxide, which causes the dough to rise, creating the fluffy texture in baked goods.
6. Which among the following will emit maximum mass of carbon dioxide , when the same quantity is burnt of all of them?
[A] Kerosene
[B] Natural Gas
[C] Gasoline
[D] Propane
Show Answer
Correct Answer: A [Kerosene]
Notes:
The carbon content of Kerosene is higher than the other fuels mentioned in the option, that is why it will emit maximum mass of carbon dioxide, when the same quantity is burnt.
7. Which of the following is the use of washing soda?
[A] softening of water
[B] manufacture of glass
[C] manufacture of paints
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
It is used for softening of water, laundering, cleaning, manufacture of glass, soap, borax, paper, paints and textile It is also extensively used as laboratory reagent.
8. Which of the following is incorrect statement about various ores?
[A] Borax is an ore of Sodium
[B] Dolomite is an ore of Aluminium
[C] The chemical formula of Magnetite is Fe3O4
[D] Flourspar is an ore of Potassium
Show Answer
Correct Answer: D [Flourspar is an ore of Potassium]
Notes:
Fluorite or Fluorspar is an ore of Calcium. It is a mineral composed of calcium fluoride. It belongs to the family of halide minerals.
9. Which of the following is true about Rutherford model of atom?
[A] it explains how the electrons are distributed around the nucleus
[B] It cannot explain about the stability of an atom around the nucleus
[C] It tells us about the energies of the electrons around the nucleus
[D] All of the above
Show Answer
Correct Answer: B [It cannot explain about the stability of an atom around the nucleus]
Notes:
A serious limitation of the Rutherford model is that it says nothing about the electronic structure of atoms i.e., how the electrons are distributed around the nucleus and what are the energies of these electrons. Also, the Rutherford model cannot explain the stability of an atom.
10. What is the order of the reaction which is independent of the concentration of reactants?
[A] Zero order
[B] First order
[C] Second order
[D] Third order
Show Answer
Correct Answer: A [Zero order]
Notes:
Order of a reaction can be 0, 1, 2, 3 and even a fraction. A zero order reaction means that the rate of reaction is independent of the concentration of reactants.
