Answer:
c
Explanation:
I hope this may help you guys
6.52 × 10⁴ L. (3 sig. fig.)
<h3>Explanation</h3>
Helium is a noble gas. The interaction between two helium molecules is rather weak, which makes the gas rather "ideal."
Consider the ideal gas law:
,
where
is the pressure of the gas,
is the volume of the gas, 
is the number of gas particles in the gas, 
is the ideal gas constant, and
is the absolute temperature of the gas in degrees Kelvins.
The question is asking for the final volume of the gas. Rearrange the ideal gas equation for volume:
.
Both the temperature of the gas, , and the pressure on the gas changed in this process. To find the new volume of the gas, change one variable at a time.
Start with the absolute temperature of the gas:
,
.
The volume of the gas is proportional to its temperature if both and stay constant.
- won't change unless the balloon leaks, and
- consider to be constant, for calculations that include .
.
Now, keep the temperature at 
and change the pressure on the gas:
,
.
The volume of the gas is proportional to the reciprocal of its absolute temperature 
if both and stays constant. In other words,
(3 sig. fig. as in the question.).
See if you get the same result if you hold constant, change , and then move on to change .
Answer is: silicon isotope with mass number 28 has highest relative abundance, this isotope is the most common of these three isotopes.
Ar₁(Si) = 28; the average atomic mass of isotope ²⁸Si.
Ar₂(Si) =29; the average atomic mass of isotope ²⁹Si.
Ar₃(Si) =30; the average atomic mass of isotope ³⁰Si.
Silicon (Si) is composed of three stable isotopes, ₂₈Si (92.23%), ₂₉Si (4.67%) and ₃₀Si (3.10%).
ω₁(Si) = 92.23%; mass percentage of isotope ²⁸Si.
ω₂(Si) = 4.67%; mass percentage of isotope ²⁹Si.
ω₃(Si) = 3.10%; mass percentage of isotope ³⁰Si.
Ar(Si) = 28.086 amu; average atomic mass of silicon.
Ar(Si) = Ar₁(Si) · ω₁(B) + Ar₂(Si) · ω₂(Si) + Ar₃(Si) · ω₃(Si).
28,086 = 28 · 0.9223 + 29 · 0.0467 + 30 · 0.031.
Answer: Isoelectronic means having the same numbers of electrons or the same electronic structure.
Explanation:
The physical and chemical properties of carbon depend on the crystalline structure of the element. Its density fluctuates from 2.25 g/cm³ (1.30 ounces/in³) for graphite and 3.51 g/cm³ (2.03 ounces/in³) for diamond. The melting point of graphite is 3500ºC (6332ºF) and the extrapolated boiling point is 4830ºC (8726ºF).
