1.
The maximum number of electrons that can be accommodated in the 3rd shell (n = 3) is:
A
8
B
18
C
32
D
10
Answer and explanation
Correct Answer: B — 18
Maximum electrons in a shell = . For n = 3: .
ObjectiveMcq
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The maximum number of electrons that can be accommodated in the 3rd shell (n = 3) is:
8
18
32
10
Maximum electrons in a shell = . For n = 3: .
During electrolysis of water, which gas is produced at the cathode?
Oxygen
Chlorine
Hydrogen
Nitrogen
At the cathode (negative electrode), reduction occurs: . So hydrogen is produced.
What is the process called when a solid directly converts to gas without passing through the liquid state?
Evaporation
Condensation
Sublimation
Fusion
Sublimation is the direct conversion of solid to gas. Examples include dry ice (CO₂) and camphor.
Noble gases are placed in which group of the periodic table?
Group 1
Group 2
Group 17
Group 18
Noble gases (He, Ne, Ar, Kr, Xe, Rn) are in Group 18 and are chemically inert due to complete electron shells.
What is the simplest hydrocarbon?
Ethane
Propane
Methane
Butane
Methane (CH₄) is the simplest hydrocarbon, containing just one carbon atom.
In the reaction , magnesium is:
Reduced
Oxidised
Neither oxidised nor reduced
Acting as an oxidising agent
Magnesium loses electrons to oxygen, so it is oxidised. Oxygen is reduced. This is a redox reaction.