A 33 gram sample of a substance that's
used to detect explosives has a k-value
of 0.1467.

From the attached graphic, Half-life = ln (.5) / k

Half-life =.693147 / 0.1142

= 6.0695884413 days

Step-by-step explanation:The value of "k" should be negative and should have units associated with it.

option 1 is correct.

step-by-step explanation:

y varies inversely with x and constant of variation is 4

the equation will be:

y = k/x

where k =4 so,

y = 4/x

if we put values of x of option 1 in the above equation and find values of y

y = 4/-2 => y =-2

y = 4/-1 => y = -4

y = 4/1 => y = 4

y = 4/2 => y =2

so, all the values of x and y are correct.

if we put values of x given in other options and find value of y we cannot find whole table satisfying the equation.

hence option 1 is correct.