Answer:
D. Sweat evaporates from your skin
Explanation:
A physical change is a reversible process, no new substance is formed. A physical change does not affect the chemical composition of a substance.
Sweat evaporation from the skin is a physical change, because the change that occur is merely a change of state, Liquid to Gaseous state, no new substance is formed.
Answer:
0.03g/mL
Explanation:
Given parameters include:
Five μL of a 10-to-1 dilution of a sample; This implies the Volume of dilute sample is given as 5 μL
Dilution factor = 10-to-1
The absorbance at 595 nm was 0.78
Mass of the diluted sample = 0.015 mg
We need to first determine the concentration of the diluted sample which is required in calculating the protein concentration of the original solution.
So, to determine the concentration of the diluted sample, we have:
concentration of diluted sample = 
=
(where ∝ was use in place of μ in the expressed fraction)
= 0.003 mg/μL
The dilution of the sample is from 10-to-1 indicating that the original concentration is ten times higher; as such the protein concentration of the original solution can be calculated as:
protein concentration of the original solution = 10 × concentration of the diluted sample.
= 10 × 0.003 mg/μL
= 0.03 mg/μL

= 0.03g/mL
Hence, the protein concentration of the original solution is known to be 0.03g/mL
Answer:
0.914moles
Explanation:
The number of moles in a substance can be got by dividing the number of atoms/molecules/particles by Avagadro's constant (6.02 × 10^23).
That is;
number of moles (n) = number of atom (nA) ÷ 6.02 × 10^23
According to this question, there are 5.5 x 10-23 molecules of H2O
n = 5.5 x 10^23 ÷ 6.02 × 10^23
n = 0.914 × 10^(23-23)
n = 0.914 × 10^0
n = 0.914 × 1
n = 0.914moles