Answer:
3
Explanation:
The half-life of a radioactive isotope is the time it takes for the mass of the sample to halve.
This can be rewritten as follows:

where
m(t) is the mass of the sample at time t
m0 is the original mass of the sample
n is the number of half-lives that passed
We see that if we take n=3, the amount of original sample left is

So 3 (3 half-lives) is the correct answer.
Yes because if 0*c equals 32*F than the higher the number the hotter it is
Answer:
Weight is used most often for measuring solid whereas volume is used most often for measuring liquid.
Explanation:
Weight is used most often for measuring solid, because solids have definite shape. Weight is usually expressed in Newton (N) because it is a function of mass and gravity. ( weight = mass x gravity).
Whereas volume is used most often for measuring liquid, usually expressed in cubic meter (m³) because liquids have no definite shape, rather they occupy the volume of their container.