Classification of Elements and Periodicity in Properties · Question 18

In which of the following options the order of arrangement does not agree with the variation of property indicated against it ?

1. I < Br < Cl < F (increasing electron gain enthalpy)
2. Li < Na < K < Rb (increasing metallic radius)
3. Al3+ < Mg2+ < Na+ < F- (increasing ionic size)
4. B < C < N < O (increasing first ionisation enthalpy)

The formation of the oxide ion, O2-(g) from oxygen atom requires first an exothermic and then an endothermic step as shown below: O(g) + e- O-(g); H = -141 kJ mol-1 O-(g) + e- O2-(g); H = +780 kJ mol-1 Thus, process of formation of O2- in gas phase is unfavourable even though O2- is isoelectronic with neon. It is due to the fact that,

1. O- ion has comparatively smaller size than oxygen atom
2. oxygen is more electronegative
3. addition of electron in oxygen results in larger size of the ion
4. electron repulsion outweighs the stability gained by achieving noble gas configuration.

The species Ar, K+ and Ca2+ contain the same number of electrons. In which order do their radii increase ?

1. Ca2+ < K+ < Ar
2. K+ < Ar < Ca2+
3. Ar < K+ < Ca2+
4. Ca2+ < Ar < K+

Which of the following orders of ionic radii is correctly represented?

1. H- > H > H+
2. Na+ > F- > O2-
3. F- > O2- > Na+
4. Al3+ > Mg2+ > N3-

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?

1. Al < Ca < O < C < F
2. Al < O < C < Ca < F
3. C < F < O < Al < Ca
4. Ca < Al < C < O < F

Identify the wrong statement in the following.

1. Amongst isoelectronic species, smaller the positive charge on the cation, smaller is the ionic radius.
2. Amongst isoelectronic species, greater the negative charge on the anion, larger is the ionic radius.
3. Atomic radius of the elements increases as one moves down the first group of the periodic table.
4. Atomic radius of the elements decreases as one moves across from left to right in the 2nd period of the periodic table.

What is the value of electron gain enthalpy of Na+ if IE1 of Na = 5.1 eV?

1. -5.1 eV
2. -10.2 eV
3. +2.55 eV
4. +10.2 eV

Which of the following oxide is amphoteric?

1. SnO2
2. CaO
3. SiO2
4. CO2

Among the elements Ca, Mg, P and Cl, the order of increasing atomic radii is

1. Mg < Ca < Cl < P
2. Cl < P < Mg < Ca
3. P < Cl < Ca < Mg
4. Ca < Mg < P < Cl

Among the following which one has the highest cation to anion size ratio?

1. CsI
2. CsF
3. LiF
4. NaF