This option is correct because boron exists in both crystalline and amorphous forms. The hydroxides and oxides of boron are acidic, not amphoteric and the melting and boiling point of boron are much higher than that of Al.

This option is correct. All the noble gases, except radon, occur in the atmosphere. XePtF₆ was the first noble gas compound prepared by N. Bartlett. The noble gases have large positive values of electron gain enthalpy due to their stable electronic configuration, they have no tendency to accept the electron.

Orthophosphoric acid (H₃PO₄) is a tribasic acid. Peroxyphosphoric acid (H₃PO₅) is a tribasic acid.

Phosphine (PH₃) belongs to C₃v point group. The H-P-H bond angles are 93.5°.

This option is correct because with the increase in size the magnitude of intermolecular Van der Waal forces increases, thus, the boiling point also increases. Because iodide ion is larger in size than chloride ion, HI has higher a boiling point than HCl and if a metal exhibits more than one oxidation state, the halides in higher oxidation state will be more covalent than the one in a lower oxidation state. For example: SnCl₄, PbCl₄, SbCl₅ and UF₆ are more covalent than SnCl₂, PbCl₂, SbCl₃ and UF₄ respectively.

Calcium and strontium crystallizes in face centered cubic structure.

Although electron gain enthalpy of fluorine is less negative as compared to chlorine, fluorine is a stronger oxidising agent than chlorine. It is due to low enthalpy of dissociation of F-F bond and high hydration enthalpy of F^-. Halogens have maximum negative electron gain enthalpy in the corresponding periods. This is because after gaining an electron, they attain the stable noble gas configuration. Thus, this option is correct.

Palladium (Pd) and silver (Ag) crystallise in face centred cubic lattice.

For the sulphates of alkaline earth metals, the cations are much smaller than the anions. On moving down the group, the change in size of the cations does not cause a significant change in ∆H_lattice, but ∆H_hydration becomes less negative. As a result, ∆H_solution becomes less negative and the solubility of alkaline earth metal sulphates decreases down the group. For the hydroxides of alkaline earth metals, the size of the anions and cations are of the same order of magnitude. On moving down the group, less energy is required to break the lattice as the size of cations increases, but the change in ∆H_hydration is comparatively small. Consequently, the ∆H_solution becomes more negative and the solubility of alkaline earth metal hydroxides increases down the group.

Tantalum (Ta) and tungsten (W) crystallises to form body centred cubic lattice.

Because their atoms are significantly smaller than those of alkali metals, alkaline earth metals have higher densities. Alkaline earth metal ions are much smaller in size than corresponding alkali metal ions and carry a higher charge. Thus, their polarizing power is greater. Electron cloud of carbonate anions are more easily distorted by alkaline earth metal ions than by alkali metal ions. Therefore, alkaline earth metal carbonates are less stable to heat and decompose to form metal oxide and carbon dioxide. Thus, this option is wrong. This option is correct because melting points in alkaline earth metals are higher than for the corresponding alkali metals. Alkaline-earth metals contribute two electrons per atom to the mobile electron cloud whereas alkali metals contribute only one electron per atom. The greater number of electrons and the smaller ionic size of the alkaline earth metals helps to increase the density of the electron cloud and thus increase the attractive forces between the mobile electrons and the cationic lattice. Alkaline earth metal ions are much smaller in size than corresponding alkali metal ions and carry a higher charge. Thus, their polarizing power is greater. Electron cloud of carbonate anions are more easily distorted by alkaline earth metal ions than by alkali metal ions. Therefore, alkaline earth metal carbonates are less stable to heat and decompose to form metal oxide and carbon dioxide.

This option is correct because NF₃ has dipole moment as it is unsymmetrical but, BF₃ has zero dipole moment because BF₃ is a symmetrical molecule.

The hydration enthalpies of alkali metal ions decrease with increase in ionic sizes. The correct order of hydration enthalpies of alkali metal ions is Li+> Na+ > K+ > Rb+ > Cs+. The thermal stability of alkali metal hydrides decreases from LiH to CsH.

This option is correct because caffeine is an alkaloid, adrenaline is a non peptide hormone, clavulanic acid is a beta lactam antibiotic and naproxen is an analgesic.

The function of erythrocytes is transport of O₂ from lungs to the tissues, the function of factor I (fibrinogen) and thrombocytes is blood coagulation, saccharide-source of energy, globulins-transport of lipids as lipoproteins and albumins-maintenance of osmotic pressure of blood plasma. Thus, this option is correct.