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 poorest conductor of heat in comparison to other options?
[A] Silver
[B] Copper
[C] Lead
[D] Mercury
Show Answer
Correct Answer: C [ Lead ]
Notes:
Silver is best conductor of heat while among metals lead is poorest conductor of heat. Cooper and aluminum are good conductor while mercury is a poor conductor.
2. Normal” rainfall is slightly acidic (and a pH of 5.6 has been assigned which might be somewhere near 5 ) because of the presence of _______?
[A] Nitric Oxide
[B] Sulphuric Acid
[C] Nitric Acid
[D] Carbonic Acid
Show Answer
Correct Answer: D [Carbonic Acid]
Notes:
Normal rainfall is slightly acidic due to the presence of carbonic acid, which forms when carbon dioxide (CO2) dissolves in water. The pH of normal rainwater is typically around 5.6, making it mildly acidic. This natural acidity is a result of the CO2 in the atmosphere, which is produced by respiration, combustion, and other natural processes.
3. 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.
4. What is Rose metal?
[A] It is an alloy of Nickel, Tin and Zinc
[B] It is an alloy of Bismuth, Copper and Palladium
[C] It is an alloy of Palladium, Tin and Lead
[D] It is an alloy of Bismuth, Tin and Lead
Show Answer
Correct Answer: D [It is an alloy of Bismuth, Tin and Lead]
Notes:
Rose metal is an alloy of Bismuth, Tin and Lead. It’s a fusible alloy with low melting point commonly used for soldering.
5. Which of the following material is used to make control rods in a nuclear reactor?
[A] Indium
[B] Boron
[C] Cadmium
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
The reaction rate is controlled through control-rods made out of neutron-absorbing materials. They are composed of chemical elements such as boron, silver, indium and cadmium that are capable of absorbing many neutrons without themselves fissioning.
6. What is the PH of human blood?
[A] 8.2
[B] 7.4
[C] 6.5
[D] 7
Show Answer
Correct Answer: B [7.4]
Notes:
Blood is normally slightly basic, with a normal pH range of 7.35 to 7.45. Usually the human body maintains the pH of blood close to 7.40.
7. Choose the incorrect acid-source pair?
[A] Citric acid – Lemon
[B] Lactic acid – Sour milk
[C] Oxalic acid – Ant sting
[D] Methanoic acid – Nettle sting
Show Answer
Correct Answer: C [Oxalic acid – Ant sting]
Notes:
An ant sting contains Methanoic acid. The sting leaves an acid which causes irritation. Use of a mild base like baking soda on the stung area gives relief.
8. Which of the following represents the cell potential?
[A] sum of the electrode potentials of the cathode and anode
[B] difference between the electrode potentials of the cathode and anode
[C] half of the sum of the electrode potentials of the cathode and anode
[D] twice the difference between the electrode potentials of the cathode and anode
Show Answer
Correct Answer: B [difference between the electrode potentials of the cathode and anode]
Notes:
The cell potential is the difference between the electrode potentials (reduction potentials) of the cathode and anode. It is measured in volts.
9. Which of these catalyst is generally used in the hydrogenation of vegetable oils?
[A] Copper
[B] Iron
[C] Nickel
[D] Manganese
Show Answer
Correct Answer: C [Nickel]
Notes:
Unsaturated hydrocarbons add hydrogen in the presence of catalysts such as palladium or nickel to give saturated hydrocarbons. This is called as Addition reaction and is commonly used in the hydrogenation of vegetable oils using a nickel catalyst.
10. Liquified Petroleum Gas (LPG) is mostly a mixture of which of the following two carbon compounds?
[A] Methane and Ethane
[B] Ethane and Propane
[C] Propane and Butane
[D] Methane and Propane
Show Answer
Correct Answer: C [Propane and Butane ]
Notes:
LPG is a Propane / Butane mixture liquefied under normal ambient temperature and moderate pressures. LPG is twice as heavy as air and half as heavy as water. LPG is colourless and odourless; hence an odorent is used to detect leaks.
