I got b 5)A sample of pure sodium-24 has an initial mass of 10.0 grams. How many grams of sodium-24 will remain at the end of 4 half-lives?
A. 0.315
B. 0.630
C. 5.00
D. 6.00
1 micro meter =

1 μm ^2 = 1 μm*1μm =

meters
1.5 μm^2 = 1.5 *

meters
μm^2 is a unit for surface. First you want to convert μm to meters which is unit for length and if you multiply units for length you get unit for surface.
Because copper has a higher electrical and thermal conductivity than iron and is not susceptible to oxidation as easily.
Answer:
B
Explanation:
The interior planet has fascinated a lot of people so a lot of theories have been made about what's in there.