Answer:
Correct answer is B.
Explanation:
Took the test and got this right. :)
Answer: There are 
molecules present in 7.62 L of 
at 
and 722 torr.
Explanation:
Given : Volume = 7.62 L
Temperature = 
Pressure = 722 torr
1 torr = 0.00131579
Converting torr into atm as follows.
Therefore, using the ideal gas equation the number of moles are calculated as follows.
PV = nRT
where,
P = pressure
V = volume
n = number of moles
R = gas constant = 0.0821 L atm/mol K
T = temperature
Substitute the values into above formula as follows.
According to the mole concept, 1 mole of every substance contains 
atoms. Hence, number of atoms or molecules present in 0.244 mol are calculated as follows.
Thus, we can conclude that there are molecules present in 7.62 L of at and 722 torr.
Answer:
The correct answer to this question is (c) 25.0 m
Explanation:
To solve this we list out the variables thus
mole fraction of sodium hydroxide = 0.310
Mole fraction = number of moles of a component ÷ total number of moles in the solution
Mole fraction = 0.310
In a saturaturated aqueous solution we have NaOH and water
∴ Number of moles of water molecules per unit = 1 - 0.310 = 0.690
However 0.690 moles of H₂O weighs = 0.690 mole × 18.01528 g/mol =12.43 g = 0.01243 kg of H₂O
But the molality = number of moles per Kilogram of H₂O
therefore molality of NaOH in the sample of solution =
(0.310 mol of NaOH )÷(0.01243 kg of H₂O)
= 24.93 mol/kg or ≅ 25.0 m
Answer: .B. 13C NMR spectra display peaks for only carbons that bear hydrogen atoms.
Explanation:
The statements that are true about 13C NMR are:
A. In 13C proton-decoupled NMR spectra, all peaks are singlets.
C 13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts.
D. 13C NMR easily differentiates between the different hybridized carbons (sp3, sp2, and sp hybridized carbons).organic-chemistry
Therefore, the option that isn't true is option B. "13C NMR spectra display peaks for only carbons that bear hydrogen atoms". This is false because 13C NMR will show every peak in the spectrum and it doesn't matter if it's only carbons that bear hydrogen atoms as everything will be shown.
The pressure of diver = atmospheric pressure + water pressure
atmospheric pressure = 750 mmHg (as given) = 750 / 760 atm = 0.987 atm
Water pressure is
P = hρg
where
h = height of water = 38 ft
1 ft = 0.3048
38 ft = 11.58 m
ρ = density = 1000 Kg / m³
g = gravitational constant = 9.81 m/s2
P = 11.58 X 1000 X 9.81 = 113599.8 Kg / m s^2 Or N /m^2
1 N / m^2 = 1 pa = 9.869 X 10^-6 atm
P = 113599.8 Pa = 1.12 atm
Total pressure = 1.12 + 0.987 atm = 2.107 atm = 2.1 atm (two significant figures)
