The amount of sample that is left after a certain period of time, given the half-life, h, can be calculated through the equation.
A(t) = A(o) (1/2)^(t/d)
where t is the certain period of time. Substituting the known values,
A(t) = (20 mg)(1/2)^(85.80/14.30)
Solving,
A(t) = 0.3125 mg
Hence, the answer is 0.3125 mg.
Half-life is defined as the amount of time it takes a given quantity to decrease to half of its initial value. The equation to describe the decay is
Nt=N0(1/2)

where N0 is the initial quantity, Nt is the remaining quantity after time t, t1/2 is the half-time. So work out the equation, t1/2 = t (-ln2)/ln(Nt/N0) = 11.5*(-ln2)/ln(12.5/100) = 3.83 days
Answer:
The percentage efficiency of the electrical element is approximately 82.186%
Explanation:
The given parameters are;
The thermal energy provided by the stove element,
= 3.34 × 10³ J
The amount thermal energy gained by the kettle,
= 5.95 × 10² J
The percentage efficiency of the electrical element in heating the kettle of water, η%, is given as follows;

Therefore, we get;

The percentage efficiency of the electrical element, η% ≈ 82.186%.
I think the correct answer from the choices listed above is option D. When a molecular compound melts, they undergo the process of phase change from solid to liquid therefore m<span>olecules arranged in a regular pattern change to an irregular pattern. Hope this answers the question.</span>
Answer:
Green light has longer wavelengths than orange light. Green light has fewer particles than orange light. Green light refracts less than orange light. That is why Green light slows down more quickly than orange light does.