Our Environment — Science STD 10 — Question

Draw a labelled diagram of human eye. What is the significance of the blind spot?

In terms of evolution, what is the significance of homology between a human hand and a wing of a bird?

When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised or reduced? Why?

State two important uses of plaster of Paris.

What happens when an acid reacts with a metal hydrogencarbonate? Write equation of the reaction which takes place.

Give the molecular formula of butane and mention the names of its two isomers. Name one fuel which contains both these isomers.

A convex lens forms a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle placed in front of the convex lens if the image is equal to the size of the object? Also, find the power of the lens.

State in brief the reaction involved in harnessing nuclear energy from uranium. Mention any two environmental hazards involved in harnessing nuclear energy.

Name the two types of spherical mirrors. What type of mirror is represented by the:

1. Back side of a shining steel spoon?
2. Front side of a shining steel spoon?

A mixture of ethyne (acetylene) and oxygen is burnt for welding. Can you tell why a mixture of ethyne and air is not used?