Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. Dalton’s name is associated with which of the following terms?
[A] Electron
[B] Proton
[C] Atom
[D] Neutron
Show Answer
Correct Answer: C [Atom]
Notes:
John Dalton introduced the atomic theory into chemistry. The main points of Dalton’s atomic theory are (1) Elements are made of extremely small particles called atoms. (2) Atoms of a given element are identical in size, mass and other properties; atoms of different elements differ in size, mass and other properties.(3) Atoms cannot be subdivided, created or destroyed. (4) Atoms of different elements combine in simple whole-number ratios to form chemical compounds. (5) In chemical reactions, atoms are combined, separated or rearranged.
2. 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.
3. A cotton wick dipped in pure honey when ignited with a matchstick will ______?
[A] Burn steadily
[B] Burn with a cracking sound
[C] Not burn at all
[D] Burn producing a large amount of smoke
Show Answer
Correct Answer: A [Burn steadily]
Notes:
A cotton wick soaked in pure honey, when lit with a matchstick, will burn consistently. This is primarily due to the high sugar content of the honey acting as fuel for the flame. Contrary to common misconceptions, honey doesn’t produce much smoke or any unusual sounds during combustion.
4. Which element is responsible for the bright red color observed during the bursting of firecrackers?
[A] Strontium
[B] Sodium
[C] Sulfur
[D] Magnesium
Show Answer
Correct Answer: A [Strontium]
Notes:
The bright red color in fireworks is due to the presence of Strontium salts. The Strontium atom, upon yielding its energy in a quick burst upon heating, emits a brilliant red light. In fact, such properties of elements are used to identify them in a flame test, a classic method in chemistry labs across the globe.
5. What is the electrical state of a molecule, considered the smallest part of matter retaining the properties of the original matter?
[A] Positive
[B] Negative
[C] Either positive or negative
[D] Neutral
Show Answer
Correct Answer: D [Neutral]
Notes:
A molecule represents the smallest portion of a substance that retains the characteristics of the substance. It’s electrically neutral because it’s made up of atoms that bond together, sharing or exchanging electrons to achieve stability. This process balances out the electrical charges of the protons and electrons, rendering the molecule as a whole electrically neutral.
6. Duralumin which is used in making aero planes is an alloy consisting of _____?
[A] Aluminum & Copper
[B] Aluminum, Copper & Manganese
[C] Aluminum, Copper, Manganese & Magnesium
[D] Aluminum and zinc
Show Answer
Correct Answer: C [Aluminum, Copper, Manganese & Magnesium]
Notes:
Duralumin is an alloy primarily composed of aluminum, copper, manganese, and magnesium. It was developed in the early 20th century and is known for its high strength-to-weight ratio, making it ideal for aircraft construction. The addition of copper enhances strength, while manganese and magnesium improve corrosion resistance and workability. Duralumin was first used in aircraft during World War I, revolutionizing aviation materials.
7. 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.
8. Which among the following acid is used to ascertain, whether pure Ghee has been adulterated with Vanaspati or Margarine?
[A] Sulphuric Acid
[B] Nitric Acid
[C] Hydrochloric Acid
[D] Boric Acid
Show Answer
Correct Answer: C [Hydrochloric Acid]
Notes:
The correct answer is Hydrochloric Acid. When testing for adulteration of pure ghee with vanaspati or margarine, hydrochloric acid is used because it reacts with the fats present in these substances, producing a distinct color change. This method is based on the principle that the presence of unsaturated fats in vanaspati or margarine will lead to a different reaction compared to pure ghee. Hydrochloric acid is commonly used in food testing due to its effectiveness in identifying such adulterants.
9. Aluminum is getting popular worldwide today as a “Green Metal”. Which among the following properties of Aluminum makes it a Green Metal?
[A] Aluminum has been providing a replacement of wood for saving forests and contributes in environment protection
[B] Aluminum is a light metal and it is resistant to corrosion
[C] Aluminum has fairly high rate of recycling and it can be re-used repeatedly without its quality deteriorating
[D] The lands after the Bauxite mining can be restored very quickly and easily
Show Answer
Correct Answer: C [Aluminum has fairly high rate of recycling and it can be re-used repeatedly without its quality deteriorating]
Notes:
Aluminum is considered a “Green Metal” primarily due to its high recycling rate. Approximately 75% of all aluminum ever produced is still in use today, as it can be recycled indefinitely without losing quality. This process saves energy—recycling aluminum uses about 95% less energy than producing new aluminum from bauxite ore. Additionally, recycling reduces greenhouse gas emissions and conserves natural resources, making aluminum a sustainable choice in various applications.
10. What is the nature of an aqueous solution of Sodium Acetate?
[A] Acidic
[B] Basic
[C] Neutral
[D] Either acidic or basic, depending on the temperature of the solution
Show Answer
Correct Answer: B [Basic]
Notes:
An aqueous solution of sodium acetate is basic in nature. This is because sodium acetate is a salt derived from a strong base (sodium hydroxide) and a weak acid (acetic acid). When dissolved in water, it undergoes hydrolysis to form sodium ions and acetate ions. The acetate ions react with water to form acetic acid and hydroxide ions, thus creating a basic solution.