If 14 g of a radioactive substance are present initially and 3 years later only 7 g remain, how much of the substance will be present after 4 yr?

5.56 g

We are given;

We need to determine the mass that will be present  after 4 years.

                                  = 4/3

Using the formula;

Therefore;

Remaining mass = 14 g × 0.5^4/3

                            = 5.56 g

Thus, the remaining mass after 4 years will be 5.56 g

none of these

step-by-step explanation:

23 + 34 add up to 57 so just inform the teacher of this really stupid mistake