Differentiate between. Melting and freezing point. Elements and compounds . Evaporation and condensation. Compound and mixture.​

Melting poing is the temperature at which a solid changes to liquid under atmospheric pressure. Freezing point is the temperature at which liquid changes to solid under atmospheric pressure.

Elements are substances that are made from one type of atom. An element cannot be broken down into any other substance. ... Compounds are substances made from atoms of different elements joined by chemical bonds. They can only be separated by a chemical reaction.

Compounds are formed because of chemical bonding between two elements. Mixtures are formed when substances are physically mixed with one another. Compounds are basically of three kinds : Ionic, metallic and covalent

practical process described pest part of scientific investigation.

because practical knowledge is powerful then therotical knowledge.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2