Improvement In Food Resources — Science STD 9 — Question

What type of sound waves are produced by a vibrating simple pendulum?

What is the number of valence electrons in the atoms of an element having atomic number 13? Name the valence shell of this atom.

Describe the energy changes which take place in a radio.

Name the laws involved in the following situation:
when person A standing on roller skates pushes another person B (also standing on roller skates) and makes him move to the right side, then the person A himself gets moved to the left side by an equal distance.

Which of the following do not exhibit Tyndall effect?
Starch solution, Sugar solution, Ink, Salt solution, Copper sulphate solution, Ammonium chloride solution, Fog, Smoke, Car exhausts.

A body goes round the sun with constant speed in a circular orbit. Is the motion uniform or accelerated?

What type of magnet is fitted on a crane to separate scarp iron objects from a heap of waste materials in factories?