B.) If the half-life of Carbon-14 is 5230 years and I start with 100 grams, how long will it take for the Carbon-14 to decay to 3.125 grams?

26150 years

Explanation:

First we need to determine the number of half lives -- not years -- it'll take for 100g (of any element) to decay to 3.125 g

First Half Life 100/2 = 50

Seconf Half Life 50/2 = 25

Third Half Life 25/2 = 12.5

Fourth Half Life 12.5/2 = 6.25

Fifth Half Life 6.25/2 = 3.125

So it'll take 5 half lives for 100g to decay to 3.125g.

If the Half Life of Carbon-14 is 5230 and it will take 5 half lives, to determine the number of years we just need to multiply 5*5230

5*5230 = 26150

This means that it will take 26150 years for 100g Carbon-14 to decay to 3.125g.

Hope this helps!

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.