Question:
How could you use a model to show the cause-and-effect relationship between Earth's rotation and the apparent motion of the stars across the night sky?
Answer:
Gravity? or density because of the pull from the sun.
The question ask for the percentage of the abundance of galium-69 where there is two isotopes of galium: the 69Ga and the 71Ga. The average atomic mass of gallium is 69.723 amu. So the formula would be <span>69.723amu=(%x)∗(68.926amu)+(1−%x)∗(70.025amu) and the answer to this is 1.58%</span>
C. The thermometer reads 100
Answer:

Explanation:
Hello,
In this case, since the Lewis theory is based on the bonds formation between atoms via the valence electrons, we can verify the chemical formula of the compound formed by strontium and nitrogen by noticing that strontium has two valence electrons as it is in group IIA, for that reason, two nitrogens should be available for bonding. Therefore, since nitrogen is in group VA, it is said that three electrons are required to attain the octet (maximum amount bonded electrons), for that reason, three strontiums are should be available for bonding. In such a way, the formula should be:

Regards.
We can use the ideal gas law equation to find the pressure
PV = nRTwhere
P - pressure
V - volume - 2.6 x 10⁻³ m³
n - number of moles - 0.44 mol
R - universal gas constant - 8.314 Jmol⁻¹K⁻¹
T - temperature - 25 °C + 273 = 298 K
substituting the values into the equation,
P x 2.6 x 10⁻³ m³ = 0.44 mol x 8.314 Jmol⁻¹K⁻¹ x 298 K
P = 419 281.41 Pa
101 325 Pa is equivalent to 1 atm
Therefore 419 281.41 Pa - 1/ 101 325 x 419 281.41 = 4.13 atm
Pressure is 4.13 atm