Answer:
a) Xbenzene = 0.283
b) Xtoluene = 0.717
Explanation:
At T = 20°C:
⇒ vapor pressure of benzene (P*b) = 75 torr
⇒ vapor pressure toluene (P*t) = 22 torr
Raoult's law:
∴ Pi: partial pressure of i
∴ Xi: mole fraction
∴ P*i: vapor pressure at T
a) solution: benzene (b) + toluene (t)
∴ Psln = 37 torr; at T=20°C
⇒ Psln = Pb + Pt
∴ Pb = (Xb)*(P*b)
∴ Pt = (Xt)*(P*t)
∴ Xb + Xt = 1
⇒ Psln = 37 torr = (Xb)(75 torr) + (1 - Xb)(22 torr)
⇒ 37 torr - 22 torr = (75 torr)Xb - (22 torr)Xb
⇒ 15 torr = 53 torrXb
⇒ Xb = 15 torr / 53 torr
⇒ Xb = 0.283
b) Xb + Xt = 1
⇒ Xt = 1 - Xb
⇒ Xt = 1 - 0.283
⇒ Xt = 0.717
The formula for the self ionization of water is 2H₂O(l)⇄H₃O⁺(aq)+OH⁻(aq)
The hydronium (H₃O⁺) is usually just referred to as a hydrogen ion or a proton (H⁺) and hydroxide (OH⁻) doesn't have another name that I am aware of. These ions do stay in solution. However the concentrations are really small and the equilibrium constant (K(w)) is 1×10⁻¹⁴.
I hope this helps. Let me know if anything is unclear.
Answer: 2.88×
atoms 
Explanation: First, using stoichiometry, we must convert this from grams to moles, then from moles to atoms.
1. For the first step, we should also look at the periodic table to find the molar mass of the compound, then use that as the denominator.

2. Now that it is converted to moles, we must convert it to atoms by multiplying it by Avogadro's number.

With this information, we know that there are
total atoms in 0.680 grams
.
I hope this helps! Pls give brainliest!! :)