Explain the difference between the mass number and average atomic mass?

 difference between mass number and atomic mass is that mass number deals with individual atoms taken into consideration separately whereas atomic mass deals with the weighted average of the element including its isotopes. bt

Explanation:

BTW mass number-the total number of protons and neutrons in a nucleus.    and   average atomic mass- mass reported on the periodic table under the element.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.

the water is warmed up by the sun and then it evaporates into the atmosphere. the sunlight warms the water by its heat. water is then cooled down and condensation takes place. the water then finally returns back to the earth by the process of precipitation in the form of rain or ice.

explanation: