I THINK 18 OR 21 I AM SORRY IF I AM WRONG BRO
A simple way to go about this is that we look at the solubility curve, on the x axis we first look at the temperature and then the corresponding value of solute/100g H2O on the y axis, from the 4 curves above only NaNO3 has a curve that can accommodate 80g of salt at 40 without being Saturated since at 40 degrees it can accommodate 105g of salt to become completely Saturated.
The answer is A. Volcanoes and earthquakes often occur near place boundaries. Volcanoes are exit points for heat from the Earth's core. And Earthquakes are caused by the tectonic places colliding along another one. For example one tectonic plate would be slowly moving south, and another next to it could collide with the South-going plate while going North, and that is what causes Earthquakes.
1) Balanced chemical equation:
2SO2 (g) + O2 (g) -> 2SO3 (l)
2) Molar ratios
2 mol SO2 : 1 mol O2 : 2 mol SO3
3) Convert 6.00 g O2 to moles
number of moles = mass in grams / molar mass
number of moles = 6.00 g / 32 g/mol = 0.1875 mol O2.
4) Use proportions with the molar ratios
=> 2 moles SO2 / 1 mol O2 = x / 0.1875 mol O2
=> x = 0.1875 mol O2 * 2 mol SO2 / 1 mol O2 = 0.375 mol SO2.
5) Convert 0.375 mol SO2 to grams
mass in grams = number of moles * molar mass
molar mass SO2 = 32 g/mol + 2*16 g/mol = 64 g/mol
=> mass SO2 = 0.375 mol * 64 g / mol = 24.0 g
Answer: 24.0 g of SO2 are needed to react completely with 6.00 g O2.