The increasing order of the strength of hydrogen bond in the following mentioned linkages
is

(i) O — H — S     (ii) O — H  — O    (iii) F – H – F   (iv) F – H – O

(1) (i) < (ii) < (iv) < (iii)                                                     

(2) (ii) < (i) < (iv) < (iii)

(3) (i) < (ii) < (iii) < (iv)                                                     

(4) (ii) < (i) < (iii) < (iv)

The boiling point of $CC{l}_4$ is higher than that of $CHC{l}_3$ because :

(1) The dipole moment of $CC{l}_4$ is greater than that of $CHC{l}_3$

(2) $CC{l}_4$ forms hydrogen bonds.

(3) $CC{l}_4$ has higher molecular mass than that of $CHC{l}_3$

(4) $CC{l}_4$ is more ionic than $CHC{l}_3$

Assertion : Compounds of ${\mathrm{Hg}}^{2+}$ ions having an ionic radius of 116 pm are move covalent in character

                   than those of ${\mathrm{Ca}}^{2+}$ ions with almost identical size (114 pm) and the same charge.

Reason : For two ions of the same size and charge, one with an (n-1)${\mathrm{d}}^{10}{\mathrm{ns}}^0.$ electronic configuration

                 will be more polarizing than a cation with an (n-1)${\mathrm{s}}^2$ (n-1)${\mathrm{p}}^6{\mathrm{ns}}^0,$ electronic configuration.

Assertion : In tetrahedral hybridisation i.e., in ${\mathrm{sp}}^3$ hybridisation all p-orbitals are involved and no

                   p-orbital is left for coming with $\mathrm{\pi }$-bonds.

Reason : Central atom can not form double bonds in the molecules or species having ${\mathrm{sp}}^3$hybridisation.

Assertion : $\mathrm{}\mathcal{}$ F bond angle P = bond angle Q but not precisely $90°.$

Reason : The molecule is slight bent T-shaped and there is repulsion between lone pairs of electrons.

Assertion : ${\mathrm{N}}_2{{\mathrm{F}}_3}^{+}$ is planar at each nitrogen atom.

Reason : ${\mathrm{N}}_3\mathrm{H},$ the bond angle $\mathrm{H}‐\mathrm{N}‐\mathrm{N}$ is $120°$ and both the $\mathrm{N}‐\mathrm{H}$ bond lengths are not equal.

Assertion : Carbon has unique ability to form $\mathrm{p\pi }-\mathrm{p\pi }$ multiple bonds with itself and with other

                  atoms of small size and high electronegativity.

Reason : Heavier elements of group ${14}^{\mathrm{th}}$ do not form $\mathrm{p\pi }-\mathrm{p\pi }$ multiple bonds with itself because

               their atomic orbitals are too large and diffuse to have effective overlapping.

Assertion : ${\mathrm{NO}}^{+}$ and ${\mathrm{CN}}^{-}$ both have same bond order and magnetism

Reason : ${\mathrm{NO}}^{+}$ and ${\mathrm{CN}}^{-}$ are isoelectornic species.

Assertion : Crystals of hydrated calcium sulphate $\left(\mathrm{gypsum} : {\mathrm{CaSO}}_4, 2{\mathrm{H}}_2\mathrm{O}\right)$ are soft and easily cleaved.

Reason : Crystals of anhydrous calcium sulphate $\left(\mathrm{anhydrite} : {\mathrm{CaSO}}_4\right)$ are very hard and very difficult

               to cleave.

 When two atoms combine to form a molecule, energy is: