Explain the observation that gave Newton the idea that sunlight is made of seven colours.

Explain the origin of the blue colour of sky.

Explain the following observations: Delta's are formed where river meets the sea.

STATE WHETHER THE FOLLOWING STATEMENTS ARE TRUE OR FALSE: The violet light travels the fastest and the red light travels the slowest of all the seven colours of white light.

Explain the following observations: Alum is added to purity drinking water.

Explain the following observations: Sky appears blue in colour.

Explain the following observations Mist or fog is formed in winter.

Explain what is observed when: An electrolyte is added to hydrated ferric oxide sol.

Explain what is observed an electrolyte, NaCl is added to hydrated ferric oxide sol.