The existence of an atom was first suggested by Democritus, the idea is then developed in 1803 by John Dalton.
According to Dalton's atomic theory, matter is made up of atoms which are inseparable and can not be destroyed further. For a given element, all atoms have identical mass and properties. Atoms of two different elements combine to form compounds and rearrangement of these atoms results in chemical reaction.
Magnesium oxide : MgO
Calcium bicarbonate: Ca(HCO3)2
aluminum carbonate: Al2(CO3)3 or C3Al2O9
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The correct answer for the following questions that are presented above are these ones:
(1) b. Pressure. The <span>physical effect can change the boiling point of a substance is the pressure.
(2) </span><span>Evaporation only occurs at the surface of a liquid. TRUE.</span><span>
(3) </span>d. freezing. The change from liquid to solid, or the reverse of melting, is called freezing.
