Answer:
21
Explanation:
Formula;
Mass number = number of protons + number of neutrons
= 9 + 12
= 21
Letters A and B are correct because burning fossil fuels can harm the atmosphere through the greenhouse effect and contribute to global warming, and can sometimes spill into the water and harm the environment.
It's in the periodic table.
See the attached picture. The number below 'Zn' is the molar mass. The closest answer choice is 65.38
Identical twins will have the e physical features such as hair color and eye color, because they were formed from the exact same egg and sperm. Fraternal twins are formed from two different eggs and sperm, so those twins will look different from each other.
Hope this help :))
