The Fundamental Unit of Life — Science STD 9 — Question

Name the quantity whose unit is:
Kilowatt-hour.

The total number of electrons in a nitrogen atom is 7. Find the number of valence electrons in it.

The window panes of houses sometimes crack when a bomb explodes even at a large distance. Why?

Name one metal and one non-metal which exist as liquids at room temperature.

Name the property of bodies (or objects) to resist a change in their state of rest or of motion.

Which of the following symbols of elements are incorrect? Give their correct symbols.
Aluminium AL

Each beehive consists of thousands of hexagonal thin-walled fragile cells. Name the material which is used to make these cells and mention the significance of the hexagonal shape of the cell.

Which of the two produces ultrasonic waves: porpoise or whale?

What name has been given to the force with which two objects lying apart attract each other?

Name the positively charged particle present in the atoms of all the elements.