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harina [27]
3 years ago
13

Element A has a half-life of 10 days. A scientist measures out 200 g of this substance. After 30 days has passed, the scientist

reexamines the sample.
How much Element A will remain in the sample?

50 g
25 g
12.5 g
100 g
Chemistry
2 answers:
Monica [59]3 years ago
6 0

Answer:

25 g of an element will remain in  the sample.

Explanation:

Initial mass of an element = N_o = 200 g

Final mass of an elemnt after time ,t = N

t = 30 days

Half life of an element =t_{\frac{1}{2}=10 days

\lambda=\frac{0.693}{t_{\frac{1}{2}}}=\frac{0.693}{10 days}=0.0693 days^{-1}

\log[N]=\log[N_o]-\frac{\lambda t}{2.303}

\log[N]=\log[200 g]-\frac{0.0693 days ^{-1}\times 30 days}{2.303}

N = 25.01 49 g ≈ 25 g

25 g of an element will remain in  the sample.

myrzilka [38]3 years ago
4 0
N=N₀*2^(-t/T)

N₀=200 g
T=10 d
t=30 d

N=200*2^(-30/10)=25 g

25 g will remain
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