Which of these numbers is in standard form?
6.5 x 5-7
0.9 x 10-7
1 x 10-7
10 x 10-7

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days