Chemical periodicity :
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1.The size of the d orbitals in Si, P, S and Cl follows the order.
(a) Cl> S > P > Si
(b) Cl> P > S > Si
(c) P > S > Si >Cl
(d) Si > P > S >Cl
Size of d-orbitals decrease with decrease in size of element. The decreasing order of size is Si > P > S >Cl.
Therefore decreasing order of size of d-orbitals is Si > P > S >Cl
2.The least basic among the following is:
(a) Al (OH)3
(b) La (OH)3
(c) Ce (OH)3
(d) Lu (OH)3
Al (OH)3→Amphoteric whereas hydroxides of lanthanoids are all base.
3.For an odd nucleon in ‘g’ nuclear orbital and parallel to I, spin and parity are
(a) 9/2 and (+)
(b) 7/2 and (+)
(c) 9/2 and (–)
(d) 7/2 and (–)
In g nuclear orbital total subshell is nine.
One odd nucleon finding in g-subshell
Total spin = 9/2
Parity=(-1)l= (-1)4 = (+)
4.The electronegativity differences is the highest for the pair
(1) Li, Cl
(b) K, F
(c) Na, Cl
(d) Li, F
Among these elements K is least electronegative and F is most electronegative. Therefore electronegativitydifference is highest for the pair K, F.
5.Among F–, Na+, O2-and Mg2+ions, those having the highest and the lowest ionic radii respectively are
(b) F– and Mg2+
All the given species are isoelectronic. Hence greater the nuclear charge, smaller will be the ionic radii.
6. 12-Crown-4 binds with the alkali metal ions in the following order:Li+>> Na+> K+> Cs+ .It is due to the
(a) Right size of cation
(b) Change in entropy being positive
(c) Conformational flexibility of crown ether
(d) Hydrophobicity of crown ether
Each crown ether binds different ions, depending on the size of the cavity.
(Reference: Advance Organic Cheimistry, Jerry March, M. Smith)