The carbon-14 activity of some ancient Peruvian corn was found to be 10 disinteg
ID: 531154 • Letter: T
Question
The carbon-14 activity of some ancient Peruvian corn was found to be 10 disintegrations/minute/gram. If present-day plant life shows 15 disintegrations/minute/gram, how old is the Peruvian com? The half-life of carbon-14 is 5, 730 years. 1455 years 1, 910 years 3, 350 years 3, 820 years 9, 080 years Which type of nuclear process requires a temperature of over a million degrees? beta particle production fission reaction alpha particle emission fusion reaction positron production The following are produced by radioactive decay process. Which one has the greatest mass? alpha particle beta particle gamma ray neutron positron Which of the following balanced equations indicates a fusion reaction? bismuth-209 + helium-4 rightarrow astatine-211 + 2 neutrons helium-2 + hydrogen-2 rightarrow-3 + hydrogen-1 plutonium-239 + neutron rightarrow americium-240 + beta particle uranium-239 rightarrow neptunium-239 + beta particle berylium-7 + electron rightarrow lithium-?Explanation / Answer
6)
Given:
Half life = 5730 years
use relation between rate constant and half life of 1st order reaction
k = (ln 2) / k
= 0.693/(half life)
= 0.693/(5730)
= 1.209*10^-4 years-1
use integrated rate law for 1st order reaction
ln[C-14] = ln[C-14]o - k*t
ln(10) = ln(15) - 1.209*10^-4*t
2.303 = 2.708 - 1.209*10^-4*t
1.209*10^-4*t = 0.405
t = 3350 years
Answer: C
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