Answer:
Sol is a colloidal suspension with solid particles in a liquid. Foam is formed when many gas particles are trapped in a liquid or solid. Aerosol contains small particles of liquid or solid dispersed in a gas. While solid solution contain solid as solute in either solid, liquid or gas.
Matter- Anything that occupies space and has mass is called matter.That is they have both mass and volume.
Apple is an example of matter because it occupies space and has mass and volume.
I think the answer is (1) Co. Because the element of Cobalt also has 2 electrons at the outer layer which is the same as Calcium. And the outer layer is an important factor which can affect the property of an element.
