There is no correct item on that list.
7.913 x 10^-6 g
3.844 * 108
6.99 X 108 ------------- All those zeros are superfluous in scientific notation but would reappear if you wrote out the number in standard notation.
2,430,000 in scientific notation is 2.43 × 106
It is 8.58*10^-7 in scientific notation
It is: 5.19*10^2
0.000000858 in Scientific Notation = 8.58 x 10-7
There is no correct item on that list.
It is: 7.0*10^9
0.000276 in Scientific Notation = 2.76 x 10-4
5.19 x 10-5
8.99 x 10-5
2.17 * 108
This does: 7 x 10^9
0.000045 = 4.5 x 10^-5 or 4.5E-5
It is: 7.0*10^9 in scientific notation