John flips 10 coins and lays them out in a straight line. how many possible combinations of heads and tails and possible?

I think that it could be 20 because you could have 10 different ones with heads and 10 different combintaions with tails.

9

Step-by-step explanation:

This can be represented by a "T Chart":

Heads  | Tails    

1 9

2 8

3 7

4 6

5 5

6 4

7 3

8 2

9 1

Hope this helps! :)

step-by-step explanation:

the answer is: d) o, f, and kr.

atomic radius of bromine (br) is 114 pm.

atomic radius of oxygen (o) is 73 pm.

atomic radius of fluorine (f) is 72 pm.

atomic radius of krypron (kr) is 112 pm.

the atomic radius of a chemical element is a measure of the size of its atom.

the atomic radius varies with increasing atomic number, but usually increases because of increasing of number of electrons.

the atomic radius decreases across the periods because an increasing number of protons, because greater attraction between the protons and electrons.