Why the enthalpy of double bond in ethene is not twice the enthalpy of single bond un ethane

Why the enthalpy of double bond in ethene is not twice the enthalpy of single bond un ethane 356 15. Find the oxidation numbers of the underlined species in the following compounds orions. PF6 OR NaHC03 . SECTION - C Short Answer Questions : o Phosphoric acid used in carbonated beverages contains 3.086% (w/w) hydrogen, 31.6104(w/ w) phosphorous and remaining oxygen. It atomic masses of hydrogen, phosphorous andoxygen are 1.01u, 31.0u and 16u respectively and if molar mass of phosphoric acid is 98.03 gmol-l what is the molecular formula of phosphoric acid? What is the difference between the terms hydrolysis and hydration? 18. Explain experimental set up for verification of Boyle's law. 19. Whydoes boron show anomalous behaviour? OR Explain anomalous property ofboron. 20. Explain Hund's rule ofmaximum multiplicity. 21. Identify the compounds 'A', 'B', and 'C' in the following sequence ofreactionsandreMi NaOWCaO complete equations. n-Butane @ In 0.1 M solution, weak electrolyte, CH3COOH is 1.3% dissociated. If 100 molecul COOH are Dlaced originallv in the so v molecules remain nonioni