S- And p-Block Elements Test - 1

PCl₅ has a trigonal bipyramidal structure. All the bonds that are present in PCl₅ are not similar. The bond length of the P-Cl bonds in the equatorial plane is different from the bond length of the P-Cl bonds in the axial plane. Hence, the statement 'P' is false.

F₂ is a stronger oxidising agent than Cl₂. Hence, the statement 'R' is false.

The I-I bond is stronger than the I-Cl bond, consequently ICl is more reactive than I₂. Hence, the statement 'Q' is true.

Pentahalides are more covalent than trihalides as the polarizing power of the central ion is greater in the higher oxidation state. This imparts a greater covalent character to the molecule. Hence, the statement 'S' is true.

The bond dissociation enthalpy (H−E) of hydrides decreases on moving down the group and consequently the thermal stability decreases.
The decreasing order of thermal stability of the group 16 hydrides is:
H₂O > H₂S > H₂Se > H₂Te > H₂Po

As we move down a group, the atomic size increases and the stability of the hydrides of group 15 elements decreases. Since the stability of hydrides decreases on moving from NH₃ to BiH₃, the reducing character of the hydrides increases on moving from NH₃ to BiH₃. Hence, the correct order of reducing character is NH₃ < PH₃ < AsH₃ < SbH₃ < BiH₃.

White phosphorus has a tetrahedral basic unit where four phosphorus atoms arranged at the four corners of a tetrahedron are joined together by a total of six single bonds.
The molecule is under tremendous strain, hence white phosphorous is highly reactive.
However, the strain is much less in case of red phosphorous on account of its polymeric structure.
Therefore, chemically, red phosphorus is much less reactive than white phosphorus and statement Q is incorrect.
In the solid state, PCl₅ exists as an ionic solid [PCl₄]⁺[PCl₆]^–, in which the cation [PCl₄]⁺ is tetrahedral and the anion [PCl₆]^– is octahedral.
Hence, statement S is incorrect.

A and R both are correct and R is the correct explanation of A.

Elements of Group 16 generally show lower value of first ionization enthalpy as compared to the corresponding periods of group 15. Due to extra stable half-filled p orbitals electronic configurations of Group 15 elements, larger amount of energy is required to remove electrons as compared to Group 16 elements.

The two oxygen-oxygen bond lengths in the ozone molecule are identical (128 pm) and the molecule is angular as expected with a bond angle of about 117^o.
Sulphur forms numerous allotropes, of which the yellow rhombic and monoclinic forms are the most important. The stable form at room temperature is rhombic sulphur, which transforms to monoclinic sulphur when heated above 369 K.

Halogens have the maximum negative electron gain enthalpy in their respective periods in the periodic table. They have the smallest size in their respective periods and therefore, the highest effective nuclear charge. As a consequence, they readily accept one electron to acquire noble gas electronic configuration.

O₂F₂ oxidises plutonium to PuF₆ and the reaction is used in removing plutonium as PuF₆ from spent nuclear fuel.

ClO₂ is used as a bleaching agent for paper pulp and textiles and in water treatment.

I₂O₅ is a very good oxidising agent and is used in the estimation of carbon monoxide.

Correct order of hydration enthalpies is Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺, because as we move from Li to Cs, the size increases and charge to radius ratio decreases, and it is difficult for the metal to be surrounded by water molecules. Hence, less energy is released when the size increases. Therefore, Li is the most heavily hydrated ion among alkali metal cations and Cs⁺ is the least hydrated ion.

Potassium imparts violet colour to an oxidising flame.