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 oxides cause the Acid rain?
[A] Carbon monoxide and carbon dioxide
[B] Nitrous oxide and sulphur dioxide
[C] Carbon dioxide and nitrous oxide
[D] Sulphur dioxide and carbon monoxide
Show Answer
Correct Answer: B [Nitrous oxide and sulphur dioxide ]
Notes:
Acid rain is caused by nitrous oxides (NOx) and sulfur dioxide (SO2) emissions, which react with water molecules in the atmosphere to form nitric and sulfuric acids. These acids then fall to the ground in rain, snow, fog, or dust particles.
2. Which among the following happens in an oxidation reaction ?
[A] Electrons are gained
[B] Electrons are lost
[C] Protons are gained
[D] Protons are lost
Show Answer
Correct Answer: B [Electrons are lost ]
Notes:
Oxidation is the loss of electrons during a reaction by a molecule, atom or ion. When oxidation occurs, an element loses electrons and its oxidation number increases .i.e. it becomes more positive.
3. Which among the following is major component of Gobar Gas?
[A] Butane
[B] Ethane
[C] Propane
[D] Metahne
Show Answer
Correct Answer: D [Metahne]
Notes:
Gobar Gas or Biogas is mostly methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulfide (H2S), moisture and siloxanes.
4. Carnotite is a mineral of which among the following metals?
[A] Lead
[B] Uranium
[C] Aluminium
[D] Iron
Show Answer
Correct Answer: B [Uranium]
Notes:
Carnotite is an ore of Uranium and comprises potassium, vanadium, water and few other elements such as calcium, barium, magnesium, iron, sodium etc. It is a yellow colored mineral.
5. What is the primary use of Phenolphthalein in chemistry?
[A] A Solvent
[B] A Dye
[C] A Catalyst
[D] A Detergent
Show Answer
Correct Answer: B [A Dye]
Notes:
Phenolphthalein is commonly employed as a pH indicator in titrations due to its distinct color change in varying pH levels. At pH 8.2, it appears colorless but turns pink as the pH increases to 10. It is not used as a solvent, catalyst or detergent. It also finds applications in forensic science for detecting latent blood stains.
6. 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.
7. In a photochemical smog, which gas causes irritation to mucous membrane and respiratory system?
[A] Nitrous oxide
[B] Sulphur dioxide
[C] Ozone
[D] Carbon monoxide
Show Answer
Correct Answer: C [ Ozone]
Notes:Ozone (O3) is the most common photochemical oxidant in photochemical smog. Inhaling ozone can cause irritation to the mucous membrane and respiratory system. Ozone can also cause chest constriction and damage to vegetation.
Other components of photochemical smog include:
- Nitrogen dioxide (NO2)
- Peroxyacetylnitrate (PAN)
- Aldehydes
Other air pollutants that can be harmful to humans include:
- Sulfur dioxide
- Volatile organic compounds (VOCs)
- Dioxins
- Polycyclic aromatic hydrocarbons (PAHs)
Carbon monoxide can cause hyperventilation, respiratory distress, and stillbirths. At high levels, carbon monoxide can even cause direct poisoning.
8. Which of the following is correct about Potassium carbonate?
[A] Its chemical formula is K CO3
[B] It is a salt which is white in colour
[C] It is used in the production of soap
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
Potassium carbonate is a salt which is white in colour. It is used in the production of soap. Its chemical formula is K2 CO3.
9. Which of the following is incorrect?
[A] Alloying helps in improving the properties of a metal
[B] An alloy is a heterogeneous mixture of two or more metals
[C] The melting point of an alloy is less than that of pure metals
[D] All of the above
Show Answer
Correct Answer: B [An alloy is a heterogeneous mixture of two or more metals]
Notes:
An alloy is a homogeneous mixture of two or more metals, or a metal and a nonmetal. Alloying helps in improving the properties of a metal. The melting point of an alloy is less than that of pure metals.
10. Brass is an alloy of which of the following metals?
[A] Copper and Tin
[B] Copper and Zinc
[C] Lead and Tin
[D] Zinc and Nickel
Show Answer
Correct Answer: B [Copper and Zinc]
Notes:
Brass is an alloy of copper and zinc (Cu and Zn). Lead is often added in concentrations of around 2% to enhance the machinability of brass.
