Question

the half - life of sodium - 22 is 2.6 years. a sample contains 800 mg of this isotope. which expression represents the mass of sodium remaining after h half - lives? s = 0.5(800)^h s = 800(0.5)^h s = 800^{0.5h} s = 800^h+0.5 done which expression relates h, the number of half - lives, and y, the number of years? h = y/2.6 retry

Explanation:

Step1: Recall half - life formula

The general formula for the amount of a substance remaining after \(h\) half - lives, when the initial amount is \(A_0\), is \(S = A_0\times(0.5)^h\).

Step2: Identify initial amount

Here, the initial mass of sodium - 22 is \(A_0 = 800\) mg.

Step3: Substitute values

Substituting \(A_0 = 800\) into the formula, we get \(S=800\times(0.5)^h\).

Answer:

B. \(S = 800(0.5)^h\)