Confused and this is timed :v

C; D; E

Step-by-step explanation:

I'll explain it to u later If u want, since its timed

i think asking google will you get the answer to that question

0.02

step-by-step explanation:

time of 9 192 631 770 periods of the radiation corresponding to the transition between the 2 hyperfine levels of the ground state of the caesium 133 atom at 0 k (but other seconds are sometimes used in astronomy)