A is the correct answer
groups are the vertical columns on the table. if you look at it, you can see that the atomic number and atomic mass increases as you go down.
They are both physical changes (change in physical structure/appearance)
hope this helps :)
By adding together the number of protons and neutrons and multiplying by 1 amu, you can calculate the mass of the atom
Answer:

Explanation:
Hello there!
In this case, according to the given information, it turns out possible for us to solve for the molarity of the KOH solution by knowing this base react in a 1:1 mole ratio with nitric acid, HNO3; thus, we can write the following equation, as their moles are the same at the endpoint:

Which in terms of molarities and volumes is:

Thus, we solve for the molarity of the base (KOH) to obtain:

Regards!