Answer: December
Explanation:
The winter solstice is around December 21, marking the date on which the Sun is lowest in the sky at noon and rises and sets farthest south.
Answer:
They have the same number of atoms. = YES
They have different masses. = YES
Explanation:
1 mol of beryllium
• 1 mol of salt
beryllium = Be = Atomic mass: 9.012182
salt = NaCl = Molar mass: 58.44 g/mol
1 mol of water
• 1 mol of hydrogen
water = H2O = Molar mass: 18.01528 g/mol
hydrogen = H = 1g/mole
Which statement is true about these substances?
They have exactly the same mass. = NO
They have different numbers of particles = NO
They have the same number of atoms. = YES
They have different masses. = YES
Avogadro constant means the number of units in one mole of any substance (defined as its molecular weight in grams) is equal to 6.02214076 × 
.
Q: A
according to this formula, we can get the mole fraction of water (n):
P(solu) = n Pv(water)
when we have Pv(solu) = 22.8 and Pv(water) = 23.8 so by substitution:
22.8 = n * 23.8
n= 0.958
- we need to get the moles of glucose:
moles of water = 500 g(mass weight) / 18 (molar weight)= 27.7 mol
n = moles of water / ( moles of water + moles of glucose)
0.958 = 27.7 / ( 27.7+ moles of glucose)
0.958 moles of glucose + 26.5 = 27.7
0.968 moles of glucose = 1.2
moles of glucose = 1.253 mol
∴ the mass of glucose = no.of glucose moles x molar mass
= 1.253 x 180 = 225.5 g
Q: B
here we also need to get n (mole fraction of water )by using this formula:
Pv(solu) = n Pv(water)
when we have Pv(solu)=132 & Pv(water)=150 so, by substition:
132= n * 150
n = 0.88
so, mole fraction of solution = 1 - 0.88 = 0.12
and we can get after that the moles of water = (mass weight / molar mass)
- no.moles of water = 85 g / 18 g/mol = 4.7 moles
- total moles in solution = moles of water / moles fraction of water
= 4.7 / 0.88 = 5.34 moles
∴ moles of the solution = total moles in solu - moles of water
= 5.34 - 4.7 = 0.64 moles solute
∴ the molar mass of the solute = mass weight of solute / no.of moles of solute
= 53.8 / 0.64 = 84 g/mole
Q: C
moles of urea (NH2)2 CO = mass weight / molar mass
= 4.49 g / 60 g /mol
= 0.07 mol
moles of methanol = mass weight / molar mass
= 39.9 g / 32 g/mol = 1.25 mol
moles fraction of methanol = moles of methanol / (moles of methanol + moles of urea )
moles fraction of methanol = 1.25 / ( 1.25+0.07) = 0.95
by substitution in Pv formula we will be able to get the vapour pressure of the solu :
Pv(solu) = n P°v
Pv(solu) = 0.95 * 89 mm Hg
∴Pv(solu) = 84.55 mmHg
Density is the ratio of mass to the volume.
The mathematical expression is given as:
Now, density of isooctane = 
Volume = 
Since, 1 gallon = 3.78 L
So, 3.8 gal = 
= 
As, 1 L = 1000 mL
Therefore, = 
Volume in mL = 
Put the values,
= 
Hence, mass of 3.8 gal of the gasoline is .
Answer: 0.405g
Explanation:
Molar Mass of Be = 9g/mol
Number of mole of Be = 0.045mol
Mass conc. Of Be = 0.045 x 9 = 0.405g
