Discuss the significance of heavy isotope of nitrogen in Meselson and Stahl's experiment.

Discuss the ecological significance of photoperiodism.

What is nutrient cycling? Discuss the significance of nutrient cycling. Discuss three aspects of nutrient cycles.

Discuss the anomalous behaviour of nitrogen.

Discuss Dumas method for estimation of nitrogen in an organic compound.

Mention the significance of Davisson and Germer's experiment. An alpha-particl e and a proton are accelerated from rest through the same potential difference V. find the ratio of de-Broglie wavelength associated with them.

(i) Discuss the anomalous behaviour of nitrogen. (ii) Give the preparation and structure of XeF_(4) . (iii) Write short note on 'Liquation'. (iv) Why is Helium used in diving apparatus ?