Physical change, a change that occurs physically, and can also be seen physically. But chemically, it's a change that occurs within the chemical, and most likely not be seen within the eyes, but, has a different charater afterward.
The periodic table is grouped by the properties of each element. They are also arranged in the order of their atomic mass. Different rows of elements are called periods. If elements lie in the same column, they are in the same group. It is helpful to us today because it helps us gain new information on the properties and the world around us. We would not have a true understanding of Chemistry if it were not for the period table.
Explanation:
reaction A is exothermic reaction as a substance is produced from two substances
and
reaction B is endothermic as two substances are formed from one complex structure
