Atoms, Molecules and Radicals — CHEMISTRY STD 7 — Question

Out of atoms and molecules, which can exist independently?

Write your observation for the following chemical reaction and name the product formed :
When sugar is heated.

Define: Solid

Statement given below is incorrect. Write the correct statement :
Oxygen is prepared in laboratory by treating hydrogen oxide with manganese dioxide.

State whether the following is physical or chemical changes.
photosynthesis —

Ripening of fruits is a desirable change.

Name the alloy used to make the body of aircraft.

What is the number of electrons donated by a magnesium atom and number of electrons accepted by a sulphur atom during their chemical combination?

Define Intermolecular space.

What happens when Magnesium burns in oxygen ? Also give the balanced chemical equation for the reaction.