Boron exists in two isotopes, boron-10 and boron-11. based on the atomic mass, which isotope should be more abundant

Boron-11.
Borons amu is 10.811 which is closer to the number 11 then it is 10 which make 11 more abundant

The boron-11 should be more abundant

Explanation:

Atomic weight in the periodic table is an average value related to the percentaje of abundance of each isotope of the element.

Given that boron has only two isotopes (10 and 11), if their abundance would be 50%:

If Ar<10.5, the boron 10 will be more abundantIf Ar>10.5 the boron 11 will be more abundant

Knowing that the boron's Ar is 10.81, we can afirm that boron-11 is more abundant.

Ithink it’s 3 as the answer.

Ithink this is what you meant. the temperature at which a liquid begins to boil is called the boiling point. the boiling point of water is 212°f or 100°c.  and at that point will start to turn into steam (gas)