<u>Answer:</u> The density of liquid is 
<u>Explanation:</u>
We are given:
Mass of cylinder,
= 65.1 g
Mass of liquid and cylinder combined, M = 120.5 g
Mass of liquid,
= 
To calculate density of a substance, we use the equation:

We are given:
Mass of liquid = 55.4 g
Volume of liquid = 49.3 mL =
(Conversion factor:
)
Putting values in above equation, we get:

Hence, the density of liquid is 
Answer:
Option C= A hydrogen bond formed between a polar side chain and a hydrophobic side chain.
Explanation:
All three given options a, b and d have common mechanism to accommodate the polar amino acid.
A= A hydrogen bond forms between two polar side chains.
B= A hydrogen bond from between a polar side chain and protein back bone.
D = hydrogen bond form between polar side chains and a buried water molecules.
All these are use to accommodate the polar amino acid.
While option C is not used. which is:
A hydrogen bond formed between a polar side chain and a hydrophobic side chain.
Given concentration of NaCl=15%
Means ,
In every 100g of Solution 15g of NaCl is present .
Now
So ,



<u>37.5g of NaCl present in 250g of solution.</u>
Quantitative observations include numerical data. Ex: 32 degrees, 10 inches, etc.