1
MCQ (Single Correct Answer)

AIPMT 2014

Which of the following orders of ionic radii is correctly represented ?
A
H$$-$$ > H$$^ \bullet $$ > H+
B
Na+ > F$$-$$ > O2$$-$$
C
F$$-$$ > O2$$-$$ > Na+
D
A$$l$$3+ > Mg2+ > N3$$-$$

Explanation

Cation loose electrons are smaller in size than the parent atom, where anions gain electrons are larger in size than the parent atom.

Hence the order is H- > H > H+
2
MCQ (Single Correct Answer)

NEET 2013 (Karnataka)

Which one of the following arrangements represents the correct order of least negative to most negative electron gain enthalpy for C, Ca, Al, F and O?
A
A$$l$$ < Ca < O < C < F
B
A$$l$$ < O < C < Ca < F
C
C < F < O < A$$l$$ < Ca
D
Ca < A$$l$$ < C < O < F

Explanation

Electron gain enthalpy becomes less negative from top to bottom in a group while it becomes more negative from left to right within a period.
3
MCQ (Single Correct Answer)

AIPMT 2012 Prelims

Identify the wrong statement in the following.
A
Amongst isoelectronic species, smaller the positive charge on the cation, smaller is the ionic radius.
B
Amongst isoelectronic species, greater the negative charge on the anion, larger is the ionic radius.
C
Atomic radius of the elements increases as one moves down the first group of the periodic table.
D
Atomic radius of the elements decreases as one moves across from left to right in the 2nd period of the periodic table.

Explanation

When positive charge on the cation increases, effective nuclear charge increases. Thus atomic size decreases.
4
MCQ (Single Correct Answer)

AIPMT 2011 Mains

What is the value of electron gain enthalpy of Na+ if IE1 of Na = 5.1 eV?
A
$$-$$ 5.1 eV
B
$$-$$ 10.2 eV
C
+2.55 eV
D
+10.2 eV

Explanation

Na $$ \to $$ Na+ + e-; $$\Delta $$H = 5.1 eV

Na+ + e- $$ \to $$ Na; $$\Delta $$H = -5.1 eV

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