Which one of the following arrangements does not give the correct picture of the trends indicated against it ?
A
F2 > Cl2 > Br2 > I2 : Bond dissociation energy
B
F2 > Cl2 > Br2 > I2 : Electronegativity
C
F2 > Cl2 > Br2 > I2 : Oxidizing power
D
F2 > Cl2 > Br2 > I2 : Electron gain enthalpy
Explanation
For Diatomic molecules (X2) of halogens the bond dissociation energy decreases in the order:
Cl2 > Br2 > F2 > I2
The oxidising power, electronegativity and relativity decrease in the order:
F2 > Cl2 > Br2 > I2
Order of Electron gain enthalpy of halogens
Cl2 > F2 > Br2 > I2
The low value of electron gain enthalpy of fluorine is probably due to small size of fluorine atom.
2
MCQ (Single Correct Answer)
AIPMT 2007
With which of the following electronic configuration an atom has the lowest ionisation enthalpy ?
A
1s2 2s2 2p3
B
1s2 2s2 2p5 3s1
C
1s2 2s2 2p6
D
1s2 2s2 2p5
Explanation
The larger the atomic size, smaller is the value of the ionisation enthalpy. Again higher the screening effect, lesser is the value of ionisation potential, So option(b) has lowest ionisation enthalpy.
3
MCQ (Single Correct Answer)
AIPMT 2007
Which one of the following ionic species has the greatest proton affinity to form stable compound ?
A
NH$$_2^ - $$
B
F$$-$$
C
I$$-$$
D
HS$$-$$
Explanation
Going from left to right across a period in the periodic table, the basicity decreases as the electronegativity of the atom possessing the lone pair of electron increases. Hence basicity of $$NH_2^-$$ is higher than F-. In moving down a group, as the atomic mass increases, basicity decreases. Hence F- is more basic than I- and HO- is more basic than HS-. Hence among the ionic species, $$NH_2^-$$ has maximum proton affinity.
4
MCQ (Single Correct Answer)
AIPMT 2007
Identify the correct order of the size of the following :
A
Ca2+ < K+ < Ar < Cl$$-$$ < S2$$-$$
B
Ar < Ca2+ < K+ < Cl$$-$$ < S2$$-$$
C
Ca2+ < Ar < K+ < Cl$$-$$ < S2$$-$$
D
Ca2+ < K+ < Ar < S2$$-$$ < Cl$$-$$
Explanation
Among isoelectronic ions, ionic radius of anions is more than that of cations. Further size of the anion increases with increase in negative charge and size of the cation decreases with increase in positive charge.
Questions Asked from Periodic Table and Periodicity
On those following papers in MCQ (Multiple Correct Answer) Number in Brackets after Paper Name Indicates No of Questions