If a frog initially contained 2 grams of carbon-14 and the half-life of carbon-14 is 5,730 years, how much carbon-14 remains in the frog after 5,730 years?

Half life is the time taken for a radioactive isotope to decay by half its original mass. In this case the half life of carbon-14 is 5.730 years. 
Using the formula;
New mass = original mass × (1/2)^n; where n is the number of half lives (in this case n=1 ) 
New mass = 2 g × (1/2)^1     
                  = 1 g
Therefore; the mass of carbon-14 that remains will be 1 g 

Adozen is 1221/12 = 1.751.75 x 12 = 21therefore, 1.75 is the answer.