NCERT Class XI Chemistry Classification of Elements and Periodicity in Properties Solutions
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Question : 31
Total: 40
The first ( Δ i H 1 ) ( Δ i H 2 ) k J m o l – 1 ( Δ e g H ) k J m o l – 1
Which of the above elements is likely to be :
(a) the least reactive element
(b) the most reactive metal
(c) the most reactive non-metal
(d) the least reactive non-metal
(e) the metal which can form a stable binary halide of the formulaM X 2
(f) the metal which can form a predominantly stable covalent halide of the formula MX (X = halogen)?
| Elements | | | |
|---|---|---|---|
| I | 520 | 7300 | –60 |
| II | 419 | 3051 | –48 |
| III | 1681 | 3374 | –328 |
| IV | 1008 | 1846 | –295 |
| V | 2372 | 5251 | +48 |
| VI | 738 | 1451 | –40 |
Which of the above elements is likely to be :
(a) the least reactive element
(b) the most reactive metal
(c) the most reactive non-metal
(d) the least reactive non-metal
(e) the metal which can form a stable binary halide of the formula
(f) the metal which can form a predominantly stable covalent halide of the formula MX (X = halogen)?
Solution:
(a) V : The element V has highest first ionization enthalpy and positive electron gain enthalpy hence, it is least reactive.
(b) II : The element II has the least first ionization enthalpy hence, it is most reactive metal.
(c) III : The element III has very high negative electron gain enthalpy hence, it is most reactive non-metal.
(d) IV : Element IV has high negative electron gain enthalpy but ionization energy is not that high hence, it is least reactive non-metal.
(e) VI : The first and second ionization energies of element VI indicate that it can form a stable binary halide.
(f) I : The element I has very low value of first ionization energy but very high second ionization energy. Hence, it will form a stable covalent halide of the formula MX.
(b) II : The element II has the least first ionization enthalpy hence, it is most reactive metal.
(c) III : The element III has very high negative electron gain enthalpy hence, it is most reactive non-metal.
(d) IV : Element IV has high negative electron gain enthalpy but ionization energy is not that high hence, it is least reactive non-metal.
(e) VI : The first and second ionization energies of element VI indicate that it can form a stable binary halide.
(f) I : The element I has very low value of first ionization energy but very high second ionization energy. Hence, it will form a stable covalent halide of the formula MX.
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