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 is the most active chemically?
[A] Chlorine
[B] Flourine
[C] Lithium
[D] Iodine
Show Answer
Correct Answer: B [Flourine]
Notes:
Fluorine is most active because it has the highest electronegativity.
2. Which of the following is an alkaline earth metal?
[A] Pottasium
[B] Lead
[C] Copper
[D] Calcium
Show Answer
Correct Answer: D [Calcium ]
Notes:
The six elements in column 2 of the Periodic table are called Alkaline Earth Metals. These include Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra).
3. The energy required to remove an electron from the outermost shell of an atom in its isolated gaseous state is called?
[A] Electron Affinity
[B] Reducing Potential
[C] Ionization Potential
[D] Shell Potential
Show Answer
Correct Answer: C [Ionization Potential ]
Notes:
Ionization potential is the energy required to remove an electron from the outermost shell of an atom in its isolated gaseous state. As we move down the group, ionization potential decreases. As we move across the period, ionization potential increases Electron affinity is the energy released on adding an electron to the outermost shell of an atom in its isolated gaseous state.
4. 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.”
5. Which among the following were not discovered by the time , Mendeleev published his periodic table?
[A] Lathanides
[B] Actinides
[C] Noble Gases
[D] Halogens
Show Answer
Correct Answer: C [Noble Gases]
Notes:
When Mendeleev published his periodic table in 1869, noble gases had not yet been discovered. The first noble gas, argon, was identified in 1894 by Lord Rayleigh and William Ramsay. In contrast, lanthanides and actinides were recognized later, but their existence was inferred from Mendeleev’s predictions. Halogens, including elements like chlorine and iodine, were known prior to Mendeleev’s work.
6. Which among the following is the correct impact of the London Forces in the Cycloalkanes?
[A] The melting and boiling points get increased
[B] The Melting and boiling points get decreased
[C] There is not impact on the melting and boiling points
[D] The melting point increases but boiling point decreases
Show Answer
Correct Answer: A [The melting and boiling points get increased]
Notes:
Please note that the Cycloalkanes with more than 20 carbon atoms are called Cycloparaffins. The cycloalkanes have the same properties as the alkanes but they have `Higher Boiling & Melting points`. This is because of the stronger dispersion forces between the atoms known as London Forces.
7. Why most of the aromatic hydrocarbons burn with a sooty flame?
[A] Because the carbon-hydrogen ratio in aromatic compounds is high
[B] Because of the presence of the strong carbon-carbon bonds
[C] Because, hydrocarbons are unsaturated
[D] Because the carbon-hydrogen ratio in aromatic compounds is low
Show Answer
Correct Answer: A [ Because the carbon-hydrogen ratio in aromatic compounds is high]
Notes:
Because the carbon-hydrogen ratio in aromatic compounds is high.
8. Which of the following chemicals is used as a molecular sieve to filter common salts from seawater to produce potable water?
[A] Graphene oxide
[B] Phosgene
[C] Sodium hypochlorite
[D] Calcium carbonate
Show Answer
Correct Answer: A [ Graphene oxide]
Notes:
Graphene oxide is used as a molecular sieve to filter common salts from seawater to produce potable water.
9. How many electrons can the s-orbital accommodate?
[A] 1
[B] 2
[C] 8
[D] 16
Show Answer
Correct Answer: B [2]
Notes:
A the s-orbital can accommodate only two electrons, two groups (1 & 2) belong to the s-block of the Periodic Table.
10. 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.
