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 of the following does not increase when we move from left to right along a period in the periodic table?
[A] Oxidising Power of elements
[B] Electronegativity
[C] Non-metallic Character
[D] Reducing power
Show Answer
Correct Answer: D [Reducing power]
Notes:
The oxidizing power of elements increases on moving left to right along a period in the periodic table. This is because electronegativity and the non-metallic character increases from left to right.
2. White Phosphorous is represented by which among the following symbols?
[A] P1
[B] P2
[C] P3
[D] P4
Show Answer
Correct Answer: D [P4]
Notes:
The most important form of elemental phosphorus from the perspective of applications and chemical literature is white phosphorus. It consists of tetrahedral P4 molecules, in which each atom is bound to the other three atoms by a single bond. This P4 tetrahedron is also present in liquid and gaseous phosphorus up to the temperature of 800 °C when it starts decomposing to P2 molecules
3. Which among the following is known as Quick Lime?
[A] CaO
[B] CaCO2
[C] Ca(OH)2
[D] CaCl2
Show Answer
Correct Answer: A [CaO]
Notes:
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline crystalline solid at room temperature.
4. 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.
5. The Helium atoms that have lost two electrons are called ________?
[A] Alpha rays
[B] Beta rays
[C] Gamma rays
[D] None of the above
Show Answer
Correct Answer: A [Alpha rays]
Notes:
Helium atoms that have lost two electrons are called alpha rays. Alpha rays are also called alpha particles or alpha radiation. Alpha particles are made up of two protons and two neutrons bound together into a particle that is identical to a helium-4 nucleus.
Alpha particles are named after the first letter in the Greek alphabet, α. They were the first nuclear radiation to be discovered.
When a helium atom loses its electrons, it is left with only the nucleus. This is called an alpha particle.
6. Which among the following is the main constituent of vegetable oil and animal fats?
[A] Glycogen
[B] Triglyceride
[C] Galactose
[D] Diglyceride
Show Answer
Correct Answer: B [Triglyceride]
Notes:
The main constituent of vegetable oil and animal fats is triglyceride. Triglycerides are composed of three fatty acids linked to a glycerol molecule. They are the most common type of fat found in the body and serve as a major energy source. In fact, triglycerides account for about 95% of the fats in the human diet.
7. What is Carbamide?
[A] A Pesticide
[B] A Fertilizer
[C] A Textile Dye
[D] An Explosive
Show Answer
Correct Answer: B [A Fertilizer]
Notes:
Carbamide is another name of Urea, an organic compound with chemical formula CO(NH2)2. This name indicates that Urea is an amide in which two –NH2 groups are joined by a carbonyl (C=O) functional group.
8. Mizoroki-Heck reaction is catalyzed by which of the following metals?
[A] Rhodium
[B] Sodium
[C] Palladium
[D] Osmium
Show Answer
Correct Answer: C [Palladium]
Notes:
The Mizoroki-Heck reaction is a cross-coupling reaction that typically involves the coupling of aryl halides with alkenes. It is primarily catalyzed by palladium (Pd) complexes. Palladium is favored due to its ability to facilitate the oxidative addition and reductive elimination steps essential for the reaction. Rhodium, while also a transition metal, is less commonly used for this specific reaction. The Mizoroki-Heck reaction is important in organic synthesis for forming carbon-carbon bonds and is widely utilized in pharmaceuticals and materials science.
9. Which of the following radical is also known as the “atmospheric detergent” ?
[A] Chlorine radical
[B] Hydroxyl radical
[C] Methyl radical
[D] Ozone radical
Show Answer
Correct Answer: B [ Hydroxyl radical]
Notes:
One of the most important chemical components of the troposphere is the ‘hydroxyl radical’: a highly reactive substance composed of an oxygen and a hydrogen atom, denoted ‘OH’. Hydroxyl radicals react with just about any other trace gas they encounter, removing them from the atmosphere.For example, OH combines with toxic carbon monoxide to generate carbon dioxide. In this sense, OH ‘cleans up’ the troposphere, and is sometimes called the detergent of the atmosphere.
10. Which of the following chemicals is also known as “Chinese snow”?
[A] Silver iodide
[B] Potassium nitrate
[C] Ammonium chloride
[D] Sodium phosphate
Show Answer
Correct Answer: B [ Potassium nitrate]
Notes:
Potassium nitrate is one of several nitrogen-containing compounds collectively referred to as saltpetre or saltpetre. It is also known as “Chinese snow”. Major uses of potassium nitrate are in fertilizers, rocket propellants and fireworks.