~The picture below shall help :)
-Hope this helped ^_^
So we know the number of moles of each compound. If we need to know the concentration we must know the number of moles that the compounds react with...
Answer: Out of the given options bonds connecting atoms in reactants break, and bonds connecting atoms in products form are the changes which takes place when a chemical change occurs.
Explanation:
A change that leads to the change in chemical composition of a substance is called a chemical change.
For example, 
Here, bond between the reactant atoms nitrogen and hydrogen is broken down.
On the other hand, bond connecting the products that is
and
is formed.
Thus,, we can conclude that out of the given options bonds connecting atoms in reactants break, and bonds connecting atoms in products form are the changes which takes place when a chemical change occurs.
Answer: True
Explanation: Frequency by definition is the number of waves that pass a fixed point given a certain amount of time. The shorter the wavelength, the higher the frequency.