Atomic number of Element A is 11 and that of element B is 9. Write the formula of the compound formed when A combines with B.

b) Find the group of these elements.

a. AB

b. 11=group 1

9=group 7

Explanation:

A=11

B=9

When they combine, that's

A+B=AB

According to the chemistry, element with atomic number 11 is sodium and element with atomic number of 9 is fluorine

So when they come it will give NaF

B. Na=11

=2,8,1

It belongs to group 1

F=9

=2,7

It belongs to group 7

When they combine by form ionic bond