Being organic and having the ability<span> to form up to 4 different covalent bonds.
</span>
Carbon has for valence electrons so it has equal chances of either adding up to these electrons or giving them away.
Note that other elements such as germanium and silicon also have these similar properties and abilities.
Unless you made a typo. D would be most accurate as it goes the furthest into the decimals
<span>The difference between heterogeneous and homogeneous mixtures is the degree at which the materials are mixed together and the uniformity of their composition. Ahomogeneous mixture is a mixture where the components that make up the mixtureare uniformly distributed throughout the mixture.</span>
Explanation:
(1) When a proton is converted into neutron then the positron emission takes place as follows.
![^{1}_{1}p \rightarrow ^{1}_{0}n + ^{0}_{+1}e](https://tex.z-dn.net/?f=%5E%7B1%7D_%7B1%7Dp%20%5Crightarrow%20%5E%7B1%7D_%7B0%7Dn%20%2B%20%5E%7B0%7D_%7B%2B1%7De)
A positron is represented by the symbol
. Therefore, when a positron emission occurs then the resultant nuclei atomic number decreases by a unit mass.
General equation representing positron emission is as follows.
![^{M}_{Z}A \rightarrow ^{M}_{Z-1}B + ^{0}_{+1}e](https://tex.z-dn.net/?f=%5E%7BM%7D_%7BZ%7DA%20%5Crightarrow%20%5E%7BM%7D_%7BZ-1%7DB%20%2B%20%5E%7B0%7D_%7B%2B1%7De)
Hence, Fluorine-18 decays by positron emission as follows.
![^{18}_{9}F \rightarrow ^{18}_{8}O + ^{0}_{+1}e](https://tex.z-dn.net/?f=%5E%7B18%7D_%7B9%7DF%20%5Crightarrow%20%5E%7B18%7D_%7B8%7DO%20%2B%20%5E%7B0%7D_%7B%2B1%7De)
Therefore, when 18F undergoes positron emission, the product nucleus is,
.
(2) Expression for the half-life of a
isotope is as follows.
![t_{\frac{1}{2}} = \frac{0.693}{\lambda}](https://tex.z-dn.net/?f=t_%7B%5Cfrac%7B1%7D%7B2%7D%7D%20%3D%20%5Cfrac%7B0.693%7D%7B%5Clambda%7D)
Initial activity, (
) = 4.00 millicuries
Activity after 95% = ![4.00 - 4.00 \times \frac{95}{100}](https://tex.z-dn.net/?f=4.00%20-%204.00%20%5Ctimes%20%5Cfrac%7B95%7D%7B100%7D)
= 0.20 millicuries
![\lambda = \frac{2.303}{t} log \frac{[N]_{o}}{[N]_{t}}](https://tex.z-dn.net/?f=%5Clambda%20%3D%20%5Cfrac%7B2.303%7D%7Bt%7D%20log%20%5Cfrac%7B%5BN%5D_%7Bo%7D%7D%7B%5BN%5D_%7Bt%7D%7D)
t = 7.912 hrs
Thus, we can conclude that it will take 7.91 hrs for 95% of the 18F to decay.