Carbon-14, which is present in all living tissue, radioactively decays via a first-order process. A one-gram sample of wood taken from a living tree gives a rate for carbon-14 decay of 13.6 counts per minute. If the half-life for carbon-14 is 5720 years, how old is a wood sample that gives a rate for carbon-14 decay of 7.9 counts per minute? A. 5.3 x 102 yr. B. 7.6 x 102 yr. C. 1.1 x 103 yr. D. 9.5 x 103 yr.

The question is incorrect, the correct question is;

Carbon-14, which is present in all living tissue, radioactively decays via a first-order process. A one-gram sample of wood taken from a living tree gives a rate for carbon-14 decay of 13.6 counts per minute. If the half-life for carbon-14 is 5720 years, how old is a wood sample that gives a rate for carbon-14 decay of 11.9 counts per minute?

C. 1.1 x 103 yr

Explanation:

A = count rate of the wood sample

Ao= count rate of a living tissue

t1/2= half life of C-14

t = time taken

From;

0.693/t1/2 = 2.303/t log Ao/A

0.693/5720 = 2.303/t log (13.6/11.9)

1.2 * 10^-4 = 2.303/t * 0.05799

1.2 * 10^-4 = 0.1336/t

t = 0.1336/1.2 * 10^-4

t = 1.1 x 103 yr

hope this

explanation:

covalent bonds

consist of pairs of electrons shared by two atoms, and bind the atoms to fixed orientation and requre high energies to break them

ionic bonds

when two atoms differ considerably in their electronegativity, then one of the atoms will lose its electron to the other atom. this results in a positively charged ion(cation) and a negatively charged ion (anion)

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