Awooden boat is discovered just south of the graet pyramid in egypt had a carbon-14 content of approximately 25% of that found in living organisms. how old is the boat? (the half-life of carbon-14 is 5,715 years.)

Because 25% is half of 0.5 and the half life of is given as 5,715, the time it takes to reach this amount should just be double the half life: 11430 years.

However, in other cases the problem may not have easy numbers, so below is a more mathematical approach.

The half life formula is .

Solving for t gives:

Given information:

Plug in given values and solve for t.

With correct significant figures, this would be 11000 years.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

im pretty sure its b