Are these ratios equivalent 18: 8 and 20: 14

No, they're not.

Step-by-step explanation:

You multiply 18×14 which = 252

Then Multiply 8×14 which = 112

(you don't multiply by 20)

It's not equivalent because it doesn't give the same number (252:112) Hope this helps!

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)