<span>Boron has a lot of different isotopes, most of which having a very short half life (ranging from 770 milliseconds for Boron-8 down to 150 yoctoseconds for boron-7). But the two isotopes Boron-10 and Boron-11 are stable with about 80.1% of the naturally occurring boron being boron-11 and the remaining 19.9% being boron-10. The weighted average weight of those 2 isotopes has the value of 10.81.
The reason they use the average mass of an element for it's atomic weight is because elements in nature are rarely single isotopes. The weighted average allows us to easily compare relative number of atoms of one element against relative numbers of atoms of another element assuming that the experimenters are getting isotope ratios close to their natural ratios.</span>
Answer is D. The periodic table rows are arranged by increasing atomic number. The atomic number is decided by how many protons they have.
Isotope ¹⁸F⁻ contains:
1) p⁺ = 9; number of protons.
Fluorine has a<span>tomic number Z = 9 (total number of protons).
2) e</span>⁻<span> = 10; </span>number of electrons.<span>
In element number of electrons and protons are the same, because element has neutral charge, but because in this example, fluorine is anion with negative charge, it has one electron more.
3) n</span>° = 9; number of neutrons.
<span>Mass number
A = 18 is total number of protons and neutrons in a nucleus, so number of neutrons is A-Z = 18-9=9.</span>
<u>Answer:</u> Carbon-carbon double bond is stronger and shorter than the single bond.
<u>Explanation:</u>
It is given that carbon-carbon double bond has greater energy than the carbon-carbon single bond.
Bond energy is directly proportional to the bond strength, which means that the double bond will have greater strength than single bond and triple bond has the greatest strength of all the bonds.
Bond energy is inversely proportional to the bond length of the carbon-carbon bond. This means that more is the bond energy, shorter will be the bond and vice-versa.
Hence, carbon-carbon double bond is stronger and shorter than the single bond.
Answer:
the correct answer is option A copper and silver
