Retro (Past 13 Year) JEE Main (P Block Elements) - JEE MCQ

Acidic strength of oxoacids depends upon the stability of conjugate base. More stable the conjugate base of an acid, stronger is the acid.

Conjugate bases stabilises by resonance.




CIO^- does not show resonance. Thus, the stability order of conjugate due to response is 

Hence, the acidic strength of given oxoacids is as follows:
 

The electronic configuration of NO[15e^-] is given by

Thus, NO possess one unpaired electron, hence it is paramagnetic in nature.  However, it dimerises at low temperatue to become diamagenetic.
 

(a) Number of electron in 

Thus, ONCI and ONO^- are not isoelectronic
(b) O₃ has bent shape structure.
Central atom O is sp²-hybridised with one lone pair of electrons.

(c) Ozone is violet black in solid state.
(d) O₃ has no unpaired electrons, thus it is diamagnetic.
Hence, all the given statements are correct.

(a)Thermal stability of the hydrides decreases as we go down the group in periodic table for group 15 (N-family).

(b) Due to absence ofd-orbital, nitrogen cannot formc/m-pm bond, thus it is correct.
(c) The N—N bond (BE 160 kJ mol^-1) is weaker than P—P bond (BE 209 kJ mol ^-1). Thus, it is correct.
(d) N₂O₄ can form two resonance structures.

Thus, it is correct.

The correct increasing basic strength
SbH₃ < AsH₃ < PH₃ < NH₃
NH₃ is most basic because of its small size, the electron density of electron pair is concentrated over small region.
As the size increases, the electron density gets diffused over a large surface area and hence, the ability to donate the electron pair (basicity) decreases. Hence, basic strength decreases down the group.

XeF₆ has much tendency to hydrolyse. The reverse reaction is more spontaneous.

Hypophosphorous acid (H₃PO₂) is a monobasic acid and has only one ionisable H because two H-atoms are directly attached to phosphorus.
The structure of H₃PO₂ is 

In a grop,  changes from negative to positive downwaeds.

Thus, HF is thermally stable and HI not.

Helium is not used to produce and sustain powerful superconducting magnets. All others are the uses of helium.

In Holmes signals of the ship, mixture of CaC₂ and Ca₃P₂ is used.

Phosphorus (3rd period element) can raise covalency facilitating vacant d-orbitals.
P (ground): [Ne] 3s² 3p³ 3d⁰ 
P (excited): [Ne] 3s¹ 3p³ 3d¹