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 of the following is not a non-metallic mineral?
[A] Mica
[B] Bauxite
[C] Granite
[D] Silica
Show Answer
Correct Answer: B [Bauxite]
Notes:
Non-metallic minerals are those minerals which do not contain metals. Examples of Non-Metallic minerals include limestone, mica, coal, gypsum, dolomite, phosphate, salt, granite etc.
3. PVC is a polymer of__?
[A] Propane
[B] Vinyl chloride
[C] Styrene
[D] Carbonates
Show Answer
Correct Answer: B [Vinyl chloride]
Notes:
Polyvinyl chloride (PVC) is made from the monomer vinyl chloride (CH2 =CHCl). It is used for making raincoats, handbags, toys including dolls, electrical goods and as a covering of electrical wires.
4. F block elements in the periodic table which are commonly called Lanthanides have the following atomic numbers:
[A] 57-70
[B] 57-71
[C] 58-71
[D] 58-70
Show Answer
Correct Answer: B [57-71]
Notes:
The correct answer is 2. The lanthanides are a series of 15 elements in the periodic table, from atomic numbers 57 (Lanthanum) to 71 (Lutetium). They are known for their similar properties and are often found together in nature. The range of atomic numbers for lanthanides is 57 to 71, not 57-70 or 58-70.
5. What term refers to the minimum temperature at which a combustible substance begins to ignite?
[A] Fireless Temperature
[B] Ignition Temperature
[C] Static Temperature
[D] Optimum Temperature
Show Answer
Correct Answer: B [Ignition Temperature]
Notes:
The term for the minimum temperature necessary to ignite a combustible substance is “Ignition Temperature”. It plays a critical role in fire safety and in the field of thermodynamics. Incorrect handling of substances with low ignition temperatures can lead to hazardous situations like unexpected fires or explosions. Additionally, understanding a material’s ignition temperature helps in proper storage and safe handling to prevent unwanted accidents.
6. 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.
7. Which of the following is not a form of brass?
[A] Dutch metal
[B] Prince’s metal
[C] Field’s metal
[D] Muntz metal
Show Answer
Correct Answer: C [Field’s metal]
Notes:
Field’s metal is an alloy of bismuth, indium, and tin, with the following percentages by weight: 32.5% Bi, 51% In, 16.5% Sn. Dutch metal, Prince’s metal and Muntz metal are a form of brass.
8. Which of the following metal has an ore named as ‘Cassiterite’?
[A] Bismuth
[B] Antimony
[C] Tin
[D] Uranium
Show Answer
Correct Answer: C [Tin]
Notes:
Cassiterite is a tin oxide mineral. Its chemical formula is SnO2. It is the only commercially important source of tin. Cassiterite is generally opaque.
9. What is the relation between mass and wavelength of any matter, as per de Broglie’s relation?
[A] Both are directly proportional
[B] Both are inversely proportional
[C] Both are independent of each other
[D] wavelength is twice the square of the mass
Show Answer
Correct Answer: B [Both are inversely proportional]
Notes:
According to de Broglie, every object in motion has a wave character. As per de Broglie’s relation, mass and wavelength are inversely proportional to each other.
10. 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.
