What is meant by the ground state of an atom? What is meant by the ground state of an atom? All of the quantum numbers have their lowest values (n = 1,ℓ = mℓ = 0). The electrons are in the lowest state allowed by the uncertainty principle. All of the electrons are in the lowest energy state, consistent with the exclusion principle. The principal quantum number of the electrons in the outer shell is 1.

Option (a) is the correct answer.

Explanation:

We know that ground state means in total electrons acquired by the element are present in their lowest energy level.

We calculate the azimutal numbers as follows.

                      n = l + 1

where,     n = principle quantum number  

                l = azimuthal quantum number

Values of n can be 1, 2, 3, 4 and so on. Whereas the values of l can be 0, 1, 2, 3, and so on.

Also, "m" is known as magnetic quantum number whose values can be equal to -l and +l.  

So, when n = 1 then l = 0 and m = 0.

When n = 2 then l = 1 and values of m will be equal to -1, 0, +1. As it is given that the magnetic quantum number ml = -1. Hence, it is only possible when n = 2.

And, n = 1 is the lowest energy level. Therefore, we can conclude that the ground state of an atom means all of the quantum numbers have their lowest values (n = 1,ℓ = mℓ = 0).

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hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.