Element X is a radioactive isotope such that every 90 years, its mass decreases by half. Given that the initial mass of a sample of Element X is 30 grams, how much of the element would remain after 12 years, to the nearest whole number?

approximately 27 grams

Work Shown:

Half life formula

y = A*(0.5)^(x/H)

where,

A = starting amount = 30 grams

H = half life period = 90 years

x = number of years that pass by = 12

y = amount left over after x years

Let's plug the values for x, A and H into the formula to find y

y = A*(0.5)^(x/H)

y = 30*(0.5)^(12/90)

y = 27.3516746567466

y = 27 rounding to the nearest whole number

a. 32 degrees

step-by-step explanation:

here we have to use the rule.

m∠e = 1/2 (major arc - minor arc)

m∠e = 1/2 (212 - 148)

m∠e = 1/2 (64)

m∠e = 32 degrees

answer: a. 32 degrees

you