JEE Advance - Chemistry (2020 - Paper 2 Offline - No. 1)
The 1st, 2nd and 3rd ionisation enthalpies, I1, I2 and I3, of four atoms with atomic numbers n, n + 1, n + 2, and n + 3, where n < 10, are tabulated below. What is the value of n?
Answer
9
Explanation
By observing the values of different ionisation energies, I1, I2 and I3 for
atomic number (n + 2), it is observed that there is very large difference between the second ionisation energy and first ionisation energy (I2 >> I1).
This indicates that number of valence shell electrons is 1 and atomic number (n + 2) should be an alkali metal.
Also for atomic number (n + 3), I3 >> I2. This indicates that it will be an alkaline earth metal which suggests that atomic number (n + 1) should be a noble gas and atomic number (n) should belong to halogen family. Since, n < 10; hence, n = 9 (F atom)
atomic number (n + 2), it is observed that there is very large difference between the second ionisation energy and first ionisation energy (I2 >> I1).
This indicates that number of valence shell electrons is 1 and atomic number (n + 2) should be an alkali metal.
Also for atomic number (n + 3), I3 >> I2. This indicates that it will be an alkaline earth metal which suggests that atomic number (n + 1) should be a noble gas and atomic number (n) should belong to halogen family. Since, n < 10; hence, n = 9 (F atom)
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