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 elements is the most electronegative?
[A] Chlorine
[B] Fluorine
[C] Bromine
[D] All of them have the same electronegativity
Show Answer
Correct Answer: B [Fluorine]
Notes:
Electronegativity is defined as an atom’s ability to attract an electron pair when forming a covalent bond. This property increases as you move left to right across the periodic table due to an increase in the nuclear charge’s attractive forces. It decreases as you move top to bottom, owing to the shielding effect of sub-levels and increased atomic radius, which makes electrons easier to remove. This culminates in Fluorine, being the highest and furthest to the right on the periodic table, hence it is the most electronegative.
2. Cassiterite is most important source of which of these metals?
[A] Nickel
[B] Tin
[C] Tungsten
[D] Silver
Show Answer
Correct Answer: B [Tin ]
Notes:
Cassiterite is a mineral that is primarily composed of tin dioxide (SnO2). It is the most important source of tin, and is also used as a semi-precious gemstone. Cassiterite is typically found in igneous and metamorphic rocks, and is often associated with other minerals such as quartz, feldspar, and mica. It has a high melting point and is resistant to weathering, making it a useful material for many industrial applications. The name “cassiterite” comes from the Greek word “kassiteros,” which means “tin.”
3. Charles Goodyear is known for which of the following ?
[A] Experiments on Rubber Plants
[B] Vulcanization of Rubber
[C] Invention of Radial Tyres
[D] Invention of Artificial Rubber
Show Answer
Correct Answer: B [Vulcanization of Rubber]
Notes:
Charles Goodyear, American inventor of the vulcanization process that made possible the commercial use of rubber. The Goodyear Tire and Rubber Company was posthumously named after him.
4. The Potassium graphite and Calcium Graphite can be mostly used as which among the following?
[A] Moderators
[B] Semiconductors
[C] Superconductors
[D] Lubricants
Show Answer
Correct Answer: C [Superconductors]
Notes:
Potassium graphite and calcium graphite are primarily used as superconductors. Superconductors are materials that can conduct electricity without resistance when cooled below a certain temperature. Graphite, particularly when doped with potassium or calcium, exhibits enhanced superconducting properties. Notably, the discovery of high-temperature superconductors in the 1980s revolutionized the field, leading to applications in magnetic levitation and advanced electronic devices.
5. Ilmenite, found in Indian coastal sands, is an ore of which element?
[A] Tungsten
[B] Titanium
[C] Gallium
[D] Tin
Show Answer
Correct Answer: B [Titanium]
Notes:
Ilmenite is a titanium-iron oxide mineral with the formula FeTiO3. India holds about 37% of global ilmenite reserves, primarily along the peninsular coastal regions. Ilmenite is the primary source of titanium, used in aerospace, chemical, and medical industries. The Geological Survey of India ranks ilmenite among the most abundant heavy minerals in Indian beach placers. Titanium extraction from ilmenite is commercially viable.
6. Which of the following elements have the lowest and highest boiling point in the Periodic table?
[A] Helium and Tungsten
[B] Hydrogen and Rhenium
[C] Helium and Rhenium
[D] Hydrogen and Tungsten
Show Answer
Correct Answer: C [ Helium and Rhenium]
Notes:
Helium has the lowest boiling point of all the elements at –452.074°F (–268.93°C) followed by hydrogen –423.16°F (–252.87°C). The highest boiling point for an element is that of Rhenium 10,104.8°F (5,596°C) followed by tungsten 10,031°F (5,555°C).
7. Which of these is NOT an allotropic form of carbon?
[A] Diamond
[B] Graphite
[C] Fullerene
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:
Carbon exhibits many allotropic forms; both crystalline as well as amorphous. Diamond and graphite are two well-known crystalline forms of carbon. In 1985, third form of carbon known as fullerenes was discovered.
8. What is dry ice?
[A] solidified form of Carbon dioxide
[B] frozen heavy water
[C] isotope of Hydrogen
[D] popular name of Benzene
Show Answer
Correct Answer: A [solidified form of Carbon dioxide]
Notes:
Carbon dioxide can be obtained as a solid in the form of dry ice by allowing the liquified CO2 to expand rapidly.
9. Choose the incorrect pair?
[A] Washing soda – Sodium Carbonate
[B] Caustic soda – Sodium Hydrogencarbonate
[C] Acetic acid – Ethanoic acid
[D] Bleaching powder – Calcium oxide
Show Answer
Correct Answer: D [Bleaching powder – Calcium oxide]
Notes:
Sodium carbonate is commonly known as Washing soda. Sodium Hydrogencarbonate is commonly known as Caustic soda. Ethanoic acid is commonly known as Acetic acid. calcium oxychloride is commonly known Bleaching powder.
10. If we take 1 kg of iron and let it rust, and none of the rust falls off, then the total weight will be___?
[A] Less than 1 Kg
[B] More than 1 Kg
[C] Exact 1 Kg
[D] More or Less than 1 Kg
Show Answer
Correct Answer: B [More than 1 Kg]
Notes:
If the rust stays attached to the main body or the flakes of rust that fall off are collected and weighed than the weight will increase. If you are using for example iron shavings than the chemical formula would look like this Fe(II) + O2 = FeO2 And the weight will increase by the mass of the shavings divided by the molar mass of iron times 2 times the molar mass of oxygen (in this case taking the molar mass of oxygen as a single oxygen atom not a pair). Thus, When rust forms, the mass of the iron object is increased by the mass of oxygen that has combined with some of the iron