1
MCQ (Single Correct Answer)

AIPMT 2010 Mains

Among the elements Ca, Mg, P and Cl, the order of increasing atomic radii is
A
Mg < Ca < Cl < P
B
Cl < P < Mg < Ca
C
P < Cl < Ca < Mg
D
Ca < Mg < P < Cl

Explanation

Atomic radius decreases on moving from left to right in a period. so order of sizes for Cl, P and Mg is Cl < P < Mg. Down the group size increases. So overall order is : Cl < P < Mg < Ca.
2
MCQ (Single Correct Answer)

AIPMT 2009

Amongst the elements with following electronic configurations, which one of them may have the highest ionisation energy ?
A
Ne [3s2 3p2]
B
Ar [3d10 4s2 4p3]
C
Ne [3s2 3p1]
D
Ne [3s2 3p3]

Explanation

Among the given options (a), (c) and (d), the option (d) has the highest ionisation energy because of extra stability associated with half-filled 3p-orbital. In option (b), the presence of 3d10 electrons offers shielding effect, as a result the 4p3 electrons do not experience much nuclear charge and hence the electrons can be removed easily.
3
MCQ (More than One Correct Answer)

AIPMT 2008

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.
4
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.

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