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 not a correct statement about Bitumen?
[A] It’s a mixture of highly condensed polycyclic aromatic compounds
[B] Its is soluble in Carbon Disulphide
[C] SARA analysis is used to determine bitumen chemistry
[D] All of above are correct statements
Show Answer
Correct Answer: D [ All of above are correct statements ]
Notes:
Bitumen is a mixture of organic liquids that are highly viscous, black, sticky, soluble in carbon disulfide and composed of highly condensed polycyclic aromatic hydrocarbons.
2. Which among the following is known as White Vitriol?
[A] Zinc Sulphate
[B] Zinc Chloride
[C] Zinc Phosphate
[D] Zinc oxide
Show Answer
Correct Answer: A [Zinc Sulphate]
Notes:
Zinc sulfate is the inorganic compound with the formula ZnSO4 and historically known as “white vitriol” Zinc sulfate is an inorganic compound and dietary supplement.
3. 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
4. What is the number of naturally occurring Halogens in the periodic table?
[A] 3
[B] 4
[C] 5
[D] 6
Show Answer
Correct Answer: C [5]
Notes:
fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At)
5. In a photochemical smog, which gas causes irritation to mucous membrane and respiratory system?
[A] Nitrous oxide
[B] Sulphur dioxide
[C] Ozone
[D] Carbon monoxide
Show Answer
Correct Answer: C [ Ozone]
Notes:Ozone (O3) is the most common photochemical oxidant in photochemical smog. Inhaling ozone can cause irritation to the mucous membrane and respiratory system. Ozone can also cause chest constriction and damage to vegetation.
Other components of photochemical smog include:
- Nitrogen dioxide (NO2)
- Peroxyacetylnitrate (PAN)
- Aldehydes
Other air pollutants that can be harmful to humans include:
- Sulfur dioxide
- Volatile organic compounds (VOCs)
- Dioxins
- Polycyclic aromatic hydrocarbons (PAHs)
Carbon monoxide can cause hyperventilation, respiratory distress, and stillbirths. At high levels, carbon monoxide can even cause direct poisoning.
6. Which among the following is produced when we pass chlorine into slaked lime?
[A] DDT
[B] Baking Powder
[C] Bleaching Powder
[D] Gypsum
Show Answer
Correct Answer: C [ Bleaching Powder]
Notes:
Bleaching powder is made by passing Cl2 into slaked lime. Though bleaching powder is often written as Ca(OCl)2 , it is really a mixture and not a compound.
7. Which of the following is correct about the atomic and ionic radii of the alkaline earth metals?
[A] it is smaller than corresponding alkali metals in the same periods
[B] it is larger than corresponding alkali metals in the same periods
[C] It is same as the corresponding alkali metals in the same periods
[D] None of the above
Show Answer
Correct Answer: A [it is smaller than corresponding alkali metals in the same periods]
Notes:
The atomic and ionic radii of the alkaline earth metals are smaller than corresponding alkali metals in the same periods due to the increased nuclear charge in these elements.
8. Which of the following quantum number is also known as orbital angular momentum?
[A] Principal quantum number
[B] Azimuthal quantum number
[C] Magnetic quantum number
[D] Electron spin quantum number
Show Answer
Correct Answer: B [Azimuthal quantum number]
Notes:
Azimuthal quantum number is also known as orbital angular momentum or subsidiary quantum number. It is represented by ‘l’.
9. What do we call the number of water molecules present in one formula unit of a salt?
[A] Formula number of salt
[B] Power of the salt
[C] Water of crystallisation
[D] Hydro number
Show Answer
Correct Answer: C [Water of crystallisation]
Notes:
The fixed number of water molecules present in one formula unit of a salt is called water of crystallisation. For example, one formula unit of copper sulphate has five molecules of water in it.
10. Choose the correct about Methyl Orange as an indicator?
[A] It turns red in acidic medium and green in basic medium
[B] It turns colourless in acidic medium and yellow in basic medium
[C] It turns red in acidic medium and yellow in basic medium
[D] It turns colourless in acidic medium and red in basic medium
Show Answer
Correct Answer: C [It turns red in acidic medium and yellow in basic medium]
Notes:
Methyl orange is a pH indicator for testing acids and bases. Methyl orange shows red color in acidic medium and yellow color in basic medium.
