JEE MAIN - Chemistry (2023 - 10th April Evening Shift - No. 4)
Given below are two statements: one is labelled as Assertion $$\mathbf{A}$$ and the other is labelled as Reason $$\mathbf{R}$$
Assertion A : The energy required to form $$\mathrm{Mg}^{2+}$$ from $$\mathrm{Mg}$$ is much higher than that required to produce $$\mathrm{Mg}^+$$
Reason $$\mathbf{R}: \mathrm{Mg}^{2+}$$ is small ion and carry more charge than $$\mathrm{Mg}^{+}$$
In the light of the above statements, choose the correct answer from the options given below.
Explanation
The correct answer is Option C: Both A and R are correct and R is the correct explanation of A.
- Assertion A: The energy required to form Mg2+ from Mg is much higher than that required to produce Mg+.
This is true because it takes more energy to remove two electrons from an atom than it does to remove one electron. The second electron is more tightly bound to the nucleus than the first electron, so it requires more energy to remove it.
- Reason R: Mg2+ is a small ion and carry more charge than Mg+.
This is also true. Mg2+ has a smaller radius than Mg+ because it has lost two electrons. The smaller radius means that the protons in the nucleus are more tightly packed together, which makes the charge of the nucleus more effective at attracting the electrons. This makes it more difficult to remove an electron from Mg2+ than it is to remove an electron from Mg+.
The reason is the correct explanation of the assertion because it explains why it takes more energy to form Mg2+ than it does to form Mg+. The smaller radius of Mg2+ and the higher charge of the nucleus make it more difficult to remove electrons from Mg2+, which requires more energy.
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