Answer:
A. 29.9
Explanation:
- An element can have differing numbers of neutrons in its nucleus, but it always has the same number of protons. The versions of an element with different neutrons have different masses and are called isotopes.
- The average atomic mass for an element is calculated by summing the masses of the element’s isotopes, each multiplied by its natural abundance on Earth.
<em>Average atomic mass of P = ∑(Isotope mass)(its abundance)</em>
∴ Average atomic mass of P = (P-29 mass)(its abundance) + (P-30 mass)(its abundance) + (P-31 mass)(its abundance) + (P-33 mass)(its abundance)
<em>Abundance of isotope = % of the isotope / 100.</em>
<em>∴ Average atomic mass of P =</em> (29)(0.327) + (30)(0.4803) + (31)(0.184) + (33)(0.0087) = <em>29.88 a.m.u ≅ 29.9 a.m.u.</em>
<em></em>
<em>So, the right choice is: A. 29.9</em>
Answer:
Option C. 1.60x10^26 molecules
Explanation:
Avogadro's hypothesis proved that that 1 mole of any substance contains 6.02x10^23 molecules.
From the above, we understood that 1 mole of CCl4 contains 6.02x10^23 molecules.
If 1 mole of CCl4 contains 6.02x10^23 molecules,
then, 265 moles of CCl4 will contain = 265 x 6.02x10^23 = 1.60x10^26 molecules
From the calculation made above, 265 moles of CCl4 contains 1.60x10^26 molecules.
