Substitution reactions The substitution reactions are the reactions which depend on the activity of metals , where the element which is more active substitutes ( replaces ) the less active one in another compound...
The salts The salts are ionic compounds that result from the the neutralization reaction of an acid and a base , they are composed due to the combination of a positive ion ( or...
Nitrogen gas properties Nitrogen gas ( N2 ) is mainly found in the atmosphere , it is also found in the Earth’s crust in the form of nitrates , it is found in the...
The electric conductivity The substances can be classified according to the electric conductivity into good conductors of electricity and bad conductors of electricity , The electrical conductivity is the ability of a material to...
Hardness of materials Some solid substances are soft at room temperature such as the rubber , and some solid substances need heat to become soft and easy to be shaped such as the metals...
The melting point The matter exists in three states which are solid , liquid and gas , and the matter can change from one state to another by heating , The change of matter...
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