8. What is the mass of a sample of glass (specific heat = 0.50 J/g°C), if it requires 490 J of heat to raise the temperature from -18.0°C to 0.0°C?

B) movement of materials into and out of the cell

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.

The answer is just took the test