The HNH angle value is higher than HPH, HAsH and HSbH angles. Why?

Assertion : HOF bond angle is higher than HOCI bond angle in HOX. 'Reason : Oxygen is more electronegative than halogens.

Bond angle in is PH_4^+ higher than that in PH_3

lonisation enthalpies' of Ce, Pr and Nd are higher than Th, Pa and U. Why?

Which one of the following statements is incorrect in relation to ionization enthalpy? (1)Ionization enthalpy increases for each successive electron.(2)The greatest increase in ionization enthalpy is experienced on removal of electron from core noble gas configuration (3)End of valence electrons is marked by a big jump in ionization enthalpy (4)Removal of electron from orbitals bearing lower n value is higher than from orbital having higher 'n' value.

Assertion: The bond angle in alcohols is slightly less than the tetrahedral angle. Reason: In alcohols, the oxygen.of -OH group is attached to carbon by a sigma bond formed by the overlap of a sp^3 hybridised orbital of carbon with sp^3 hybridised orbital of oxygen.

Why a tennis ball bounces higher on hills than in plain?

Allow light to fall at an angle of incidence greater than the critical angle . What do you observe ?