The amount remained after 42 days is 1.25 g. The correct option is c.
Half life is the time taken by a radioactive material for the radioactivity of to reduce by half its original value.
The half life equation is:
A = A₀ (½)^(t / T)
where A is the final amount, A₀ is the initial amount, t is the amount of time, and T is the half life.
Given is the value of A₀ = 10.0g, and T = 14 days.
A = 10 (½)^(t42/ 14)
A =10 x ½^(3)
A = 1.25 g
Thus, final amount left 1.25 g
Learn more about half life.
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