31 Years NEET Previous Year Questions: Classification of Elements & Periodicity in Properties - NEET MCQ

A. B. D are the configuration of Zn, Cd and Hg respectively which belongs to the same family. But c is the configuration of chlorine which belongs to halogen family.

Metallic character decreases in a period and increases in a group.

Electron affinity values are high in case of halogen because halogens have seven electrons (ns²np⁵) in the valence shell, they have a strong tendency to acquire the nearest inert gas configuration by gaining an electron from the metallic atom and form halide ions easily.

N, O and F (p-block elements) are highly electronegative non metals and will have the strongest tendency to form anions by gaining electrons from metal atoms.

Proton (H⁺) being very small in size would have very large hydration energy.

Amongst isoelectronic ions, the size of the cation decreases as the magnitude of the charge increases.

The electronic configuration of element with atomic number 33 is 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p³
As, its last shell have five electrons
and hence, its group is 10 + 5 = 15th or V A.
Hence,it lies in the 15th group.
 

Atomic volume is the volume occupied by one gram of an element. Within a period from left to right, atomic volume first decreases and then increases due to increases of nuclear charge and increase in the number of electrons in the valence shell.

In option D, after removal of second valence electron from 3s orbital, the ion formed achieves noble gas configuration. Therefore, to remove the third electron from 2p orbital, a lot of energy is required. Thus, there is an abnormally high difference between second and third ionization enthalpies.

Non-metal like halogens are strongest oxidizing agents according to electrochemical series they form acidic oxides like SO₂ they form anion by electron gain and they are highly electronegative.
(fluorine is most electronegative element of whole periodic table)

Atomic number of the given element is 15 and it belongs to 5th group. Therefore atomic number of the element below the above element = 15 + 18 = 33.

Electronic configuration of element with atomic number 118 will be [Rn]5f¹⁴6d¹⁰ 7s²7p⁶. Since its elctronic configuration in the outer most orbit (ns²np⁶) resemble with that of inert or noble gases, therefore it will be noble gas element.

Greater is the positive charge on atom, large is effective nuclear charge. Hence smaller is the size

In a period on moving from left to right ionic radii decreases.

(a) So order of cationic radii is Cr²⁺ > Mn²⁺  > Fe²⁺ > Ni²⁺ and

(b) Sc > Ti > Cr > Mn (correct order of atomic radii)

(c) For unpaired electrons Mn²⁺ (Five)
Ni²⁺ (Two) < Co²⁺ (Three)<Fe²⁺ (Four )

(d) For unpaired electrons Fe²⁺(Four) < Co²⁺ (Three) <Ni²⁺ (Two)<Cu²⁺(One)

First ionisation potential of Be is greater than boron due to following configuration ₄Be=1s²,2s² ₅B=1s²,2s²2p¹ Order of attraction of electrons towards nucleus 2s>2p, so more amount of energy is required to remove the electron with 2sorbital in comparison to 2p orbital.

Mg = 1s² 2² 2p⁶ 3s² After removing of 2 electron, the magnesium acquired noble gas configuration hence removing of 3rd electron will require large amount of energy.

Be – 1s²2s²; B – 1s²2s²2p1; C – 1s²2s²2p²; N – 1s²2s²2p³; O – 1s²2s²2p⁴. IP increases along the period. But IP of Be > B. Further IP of O < N because atoms with fully  or partly filled orbitals are most stable and hence have high ionisation energy.

Along the period, I.P. generally increases but not regularly. Be and B are exceptions. First I.P. increases in moving from left to right in a period, but I.P. of B is lower than Be.

The electronic configuration clearly suggest that it is a d-block element (having contiguration (n – 1) d^{1– 10} ns^{0 – 2}) which starts from III B and goes till II B. Hence with d³ configuration it would be classified in the group.

This is because of inter-electronic replusions between lone pairs.

Among the given options, only Fe shows variable oxidation states so it can form two chlorides, viz. FeCl₂ and FeCl₃.

Ionic radii are inversely proportional to effective nuclear charge.
Ionic radii in the nth orbit is given as

when n = principal quantum number
Z-effective nuclear change.

Due to odd number of electr on s in ClO₂.

Therefore   

The amount of energy released when an electron is added to an isolated gaseous atom to produce a monovalent anion is called electron gain enthalpy.
Electron affinity value generally increase on moving from left to right in a period however there are exceptions of this rule in the case of those atoms which have stable configuration. These atoms resist the addition of extra electron, therefore  the low value of electron affinity

On the other hand Cl because of its compariti very bigger size than F, allow the addition of an extra electron more easily.

For i soelectronic species, size of anion increases as negative charge increases whereas size of cation decreases with increase in positive charge. Further ionic radii of anions is more than that of cations. Thus the correct order is          
Ca⁺⁺ < K⁺ < Ar < Cl^– < S^{– –}

The electronic configuration 1s² 2s²2p⁵ 3s¹ shows lowest ionisation energy because this configuration is unstable due to the presence of one electron is s- orbital. Hence, less energy is required to remove the electron.

Proton affinity decreases in moving across the period from left to right due to increase in charge, within a group the proton affinities decreases from to p to bottom.
Nitrogen family > Oxygen family > Halogens

The stability of +1 oxidation state increases from  aluminium to thallium i.e.
Al < Ga < In < Tl

Due to inert pair effect, as we move down the group. Lower oxidation state stablises so order of +1 oxidation state is:

Al < Ga < In < Tl

The smaller the atomic size, larger is the value of ionisation potential. Further the atoms having half filled or fully filled orbitals are comparitively more stable, hence more energy is required to remove the electron from such atoms.

Among the isoelectronic species, size increases with the increase in negative charge. Thus S^2– has the highest negative charge and hence largest in size followed by Cl^–, K⁺ and Ca.