Explain how you can locate the Pole Star with the help of Ursa Major.

Explain how can you take care of your eyes .

Mention three different modes of propagation used in communication system. Explain with the help of a diagram how long distance communication can be achieved by ionospheric reflection of radio waves.

Why do different colours get separated when a white light passes through a prism ? How can we recombine the components of white light after a prism has separated them ? Explain with the help of a figure.

Explain how liquid hydrogen can be used as a fuel

How do Mendel's experiments show that traits may be dominant or recessive? explain it with the help of a cross.

Differentiate between roasting and calcination. Explain the two with the help of suitable chemical equatiosn. How is zinc extracted from its ore?