1. The answer is option E, that is None of the above is correct.
As a polymer becomes more crystalline,
its melting point doesn't decreases, its density doesn't decreases, its stiffness doesn't decreases and its yield stress doesn't decreases.
2. The answer is option B, that is the molecules are arranged in sheets, with their long axes parallel and their ends aligned as well.
In the smectic A liquid-crystalline phase, molecules are arranged in sheets, with their long axes parallel and their ends aligned as well.
3. For a substitutional alloy to form, the two metals combined must have similar atomic radii and chemical bonding properties.
Answer:
In a chemical reaction, there is a change in the composition of the substances in question; in a physical change there is a difference in the appearance, smell, or simple display of a sample of matter without a change in composition. Although we call them physical "reactions," no reaction is actually occurring.
26.25g
Explanation:
Given parameters:
Percentage of NaCl in ocean water = 3.5%
Mass of given seawater = 750g
Unknown:
Mass of NaCl in the seawater = ?
Solution:
This is a simple percentage problem:
We have been given that ocean water contains 3.5% of NaCl;
Therefore;
Mass of NaCl in seawater = Percentage of NaCl in ocean water x Mass of seawater
Mass of NaCl in seawater = 
x 750g = 26.25g
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