Answer:
francium
Explanation:
the atomic radius increases from top to bottom in a group, and decreases from left to right across a period.
Answer:
Bro I got notification of this question but soory I don't know the answer Hope you understand me
a is the answer because all of the other answers are wrtong
For any given element the mass number can be found by adding the protons and the neutrons.
In this case its 10 protons plus 11 neutrons which gives us 21 as the mass number.
