Answer:
[α] = -77.5° / 
Explanation:
Given;
Mass of optically pure substance in the solution = 10 g
Volume of water = 500 mL
Length of the polarimeter, l = 20 cm = 20 × 0.1 dm = 2 dm
measured rotation = - 3.10°
Now,
The specific rotation ( [α] ) is given as:
[α] = 
here,
α is the measured rotation = -3.10°
c is the concentration
or
c = 
or
c = 
or
c = 0.02 g/mL
on substituting the values, we get
[α] = 
or
[α] = -77.5° / 
Answer:
c. 15 g Kr
Explanation:
The amount of a gas (Moles) is directely proportional to its pressure. That means the higher amount of moles, the highest pressure and vice versa.
Using molar mass of the compounds (Ne=20.2g/mol, Ar = 39.9g/mol, Kr = 83.8g/mol, CO₂ = 44 g/mol and F₂ = 38.0g/mol), moles of 15.0g of each gas are:
Ne = 15g ₓ (1mol / 20.2g) = <em>0.74 moles of Ne</em>
Ar = 15g ₓ (1mol / 39.9g) = <em>0.38 moles of Ar</em>
Kr = 15g ₓ (1mol / 83.8g) = <em>0.18 moles of Kr</em>
CO₂ = 15g ₓ (1mol / 44g) = <em>0.34 moles of CO₂</em>
F₂ = 15g ₓ (1mol / 38g) = <em>0.39 moles of F₂</em>
<h3>As 15g of Kr contains the less quantity of moles, this sample will con have the lowest pressure</h3>
Since a water molecule is H2O, you would divide 126 hydrogen molecules by 2, and you would get 63. That means you have 63 double hydrogen molecules, and 58 oxygen molecules to pair up with them. So that means you could have 58 molecules of water, with 5 double hydrogen molecules, so basically 10 extra molecules of hydrogen along with the H2O molecules. Hope I helped! :)