Molecular oxygen and Hydrogen fluoride.
Explanation:
Definition:
Hydrogen bonding:
It is a type of dipole-dipole attraction between the hydrogen atom and more electronegative atoms.
In hydrogen bonding mostly the highly electronegative atoms are fluorine, nitrogen and oxygen.
Explanation:
In given compound such as methane CH₄ the electronegativity of carbon is 2.55 while that of hydrogen is 2.2 so there is smaller electronegativity difference that's why it can not form hydrogen bond.
In case of molecular oxygen the electronegativite atom oxygen is present. It can form hydrogen bonds with water. its electronegativity is 3.44.
In case of hydrogen fluoride the electronegativity atom fluorine is present. It will form hydrogen bonds with water. Its electronegativity is 3.98. So it is more likely to take part in hydrogen bonding.
Increasing the surface area of a solid reactant exposes more of its particles to attack. This results in an increased chance of collisions between reactant particles, so there are more collisions in any given time and the rate of reaction increases.
I hope you helped^_^