The isotope 14C has a half life of 5,770 years.?

Question

The isotope 14C has a half life of 5,770 years.

A piece of wood originally contained 4.00 g of 14C.

Today it contains only 1.00 g of that isotope.

About how old is the piece of wood?

a. 11,540 years

b. 17,310 years

c. 5,770 years

d. 23,080 years

e. 1,443 years

Answer 1

In order for there to be only 1g, the 14C must have undergone 2 half lives.  Therefore (5770 x 2) = 11540.

Answer 2

2 periods 5770*2=11540 years

answer a