Chemistry - Hydrogen and Its compound Question with Solution | TestHub

(i) Ortho hydrogen < Para hydrogen (Stability at low temperature) - INCORRECT. Para hydrogen is more stable at low temperatures.

(ii) Ethanol < Glycerol (Viscosity) - INCORRECT. Glycerol has more -OH groups, leading to stronger intermolecular hydrogen bonding and higher viscosity.

(iii) $D_2>He$ (Boiling Point) - INCORRECT. Boiling point of $D_2$ is 23.6 K, He is 4.2 K.

(iv) $HF<H_{2}O$ (Melting point) - INCORRECT. $H_{2}O$ has a higher melting point due to more extensive hydrogen bonding (each $H_{2}O$ can form 4 H-bonds, HF forms 2).

(v) $H_{3}B{O}_3<B{F}_3$ (Melting point) - INCORRECT. $H_{3}B{O}_3$ is a solid with extensive hydrogen bonding, $B{F}_3$ is a gas.

(vi) $N{H}_3>Sb{H}_3$ (Boiling point) - INCORRECT. $N{H}_3$ has strong hydrogen bonding, but $Sb{H}_3$ has stronger van der Waals forces due to larger size, making its boiling point higher.

(vii) $H_2{O}_2>H_{2}O$ (Strength of hydrogen bond) - INCORRECT. The O-H bond in $H_{2}O$ is more polar than in $H_2{O}_2$, leading to stronger individual H-bonds in $H_{2}O$.

(viii) $H_{2}O<D_{2}O$ (Freezing point) - CORRECT. $D_{2}O$ has a higher freezing point (3.82 °C) than $H_{2}O$ (0 °C).

(ix) $H{F}_2^{\Theta }>HF$ (Strength of hydrogen bond) - CORRECT. The hydrogen bond in $H{F}_2^{\Theta }$ is exceptionally strong and symmetrical.

(x) $D_{2}O>H_{2}O$ (Bond energy) - CORRECT. The O-D bond is stronger than the O-H bond due to the isotope effect (zero-point energy difference).

Number of incorrect orders = 7