Which of the following is NOT true? A) 4 x 1/2 = 4/1 x 1/2

B) 1/2 divide 4 = 1/2 x 1/4

C) 4 divide 1/2 = 4 x 2

D) 1/2 divide 4 = 1/2 x 4/1

Please help!! :/

The half-life of a certain material is 0.002 second. approximately how much of a 14-gram sample will be left after 0.004 second? a. 12 grams b. 3.5 grams c. 0.06 gram d. 7 grams