How many grams of ^16N will be left from a 16.0 g sample after 21.6 s?

2 g

Explanation:

From the question given above, the following data were obtained:

Original amount (N₀) = 16 g

Time (t) = 21.6 s

Amount remaining (N) =?

Next, we shall determine the number of half-lives that has elapse. This can be obtained as follow:

Time (t) = 21.6 s

Half-life (t½) of ¹⁶N = 7.13 s

Number of half-lives (n) =?

n = t / t½

n = 21.6 / 7.13

n = 3

Finally, we shall determine the amount of ¹⁶N remaining. This can be obtained as follow:

Original amount (N₀) = 16 g

Number of half-lives (n) = 3

Amount remaining (N) =?

N = 1/2ⁿ × N₀

N = 1/2³ × 16

N = 1/8 × 16

N = 2 g

Thus, the amount of ¹⁶N remaining is 2 g

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it is b that is the answer.