Answer:
a, b, d and f
Explanation:
To find which equation will have a a mass less than 50 mg after 2 hours, we just need to use the value of x = 2 and then verify if the values of y are less than 50:
a. y = 100*(0.5)^2 = 25 -> apply
b. y = 500*(0.3)^2 = 45 -> apply
c. y = 80*(2)^2 = 320 -> doesn't apply
d. y = 10*(1.2)^2 = 14.4 -> apply
e. y = 30*(1.5)^2 = 67.5 -> doesn't apply
f. y = 80*(0.2)^2 = 3.2 -> apply
g. y = 100*(2)^2 = 400 -> doesn't apply