Momentum is a VECTOR quantity because it involves MAGNITUDE AND DIRECTION.
A vector quantity is a quantity which has both magnitude and direction. The formula for momentum is mass x velocity. The mass is a scalar quantity while the velocity is a vector quantity; scalar multiply by vector quantity will give vector quantity .<span />
Set this up as
10 = 40 (1/2)t/28
and solve for t in years.
10/40 = (1/2)t/28
log(0.25) = (t/28) log(0.5)
t = 28 log(0.25) / log(0.5) years = 56 years
Test the answer:
56 years = 2(28 years) = 2 half-lives, so the remaining amount should be 1/2 of 1/2 of the initial amount, i.e. 1/4 of the initial amount, and 10 mg = 1/4 of 40 mg.
Black Bush Poulder is not one of Guyana's sugar estate.
Happy Studying! ^=^
I think the answer is A hope i helped