Statement I : Bond length in C–C > N–N > O–OStatement II : Bond enthalpy in C–C > N–N > O–O

Left to right in a period  Atomic radius decreases∴size of C > N > O∴C–C > N–N > O–O …..Bond lengthGenerallyBond  enthalpy  ∝ 1Bond  length∴  Expected trend of Bond enthalpy          C–C < N–N < O–OBut both ‘N’ and ‘O’ contain lone pairs.  Due to the repulsions between lone pairs of adjacent atoms in N–N and O–O their bond enthalpies are very low.∴Experimental bond enthalpy     C–C > N–N > O–O