The World of Metals and Non-metals — Science STD 7 — Question

(a) Name the watch that have an electric circuit with one or more cells.
(b) Name the ancient time measuring device.

Draw the orientation of the Big Dipper in the sky with respect to the pole star after two hours intervals. You find pole star appears nearly stationary while all the stars move around it in the sky. Why?

Write short notes on sexual reproduction in plants.

Which type of motion is more common in daily life—uniform or non-uniform? Provide three examples from your experience to support your answer.

Describe the process of neutralisation with the help of an example.

'A' got her gall bladder removed surgically as she was diagnosed with stones in her gall bladder. After the surgery, she faced problems in digestion of certain food items, when consumed in bulk. Can you tell which kind of food items would they be and why?

A sewage treatment plant involves a few steps. Aeration tank, grit and sand removal tank, second sedimentation tank, bar screen, first sedimentation tank.
(i)Arrange all the above steps in the correct order in which they occur in the sewage treatment plant.
(ii)Which step gives most of the sludge?

Give two examples each of natural slow change and desirable change.

Table : Presence of starch in green and non-green parts of the leaves of plants

Respiration can occur in two different manners. Briefly explain the process of aerobic respiration. How does it differ from anaerobic respiration?