Answer: Option (a) is the correct answer.
Explanation:
When two or more atoms are chemically combined together then the product formed is known as a molecule.
These atoms can be bonded through either covalent or ionic bonds.
For example, a water molecule consists of two hydrogen atoms combined with an oxygen atom. Chemical formula of water is 
.
Thus, we can conclude that an element can be made of many elements.
The three evidences that show that the particles of substances are in continuous motion are given below:
1. DIFFUSION: Diffusion is the movement of particles of a substance through a medium, from a region of higher concentration to a region of lower concentration. Particles of substances (solid, liquid or gas) tend to move from an area where more of them are present to an area where only few are present until they are evenly distributed. For example, a can of gasoline left in an open air can easily catch fire because the particles of gasoline can be easily carried by air to the nearest source of ignition.
2. OSMOSIS: Osmosis is the process by which solvent molecules move from a less concentrated solution to a more concentrated solution through a semi permeable membrane; the movement typically continues until the concentrations of solutes on both sides of the membrane are equal. Osmosis is a very crucial process in the biological systems of living organisms, where the plasma membrane, which is semi permeable in nature only allow specific small particles to pass through. Water molecules pass through the plasma membrane by diffusion via the phospholipid bilayers; osmosis thus provide the major mean via which water is moved in and out of living cells
3. BROWNIAN MOVEMENT: When a pollen grain, which is suspended in a drop of water is observed under a microscope, it will be seen that the pollen is moving about in a zig-zag manner. The zig zag movement of the pollen is due to the continuous movement of the particles of water on which the pollen was suspended. This phenomenon was first observed by a botanist, a British scientist called Robert Brown in 1827 and that was why the phenomenon was named after him.
A. is right because the waves are at the top and as u get deper of course the energy will decrease
I'm pretty sure its metals.
