Answer:
b. the 20 amino acids found in proteins differ in the composition of their R groups, which may be either polar or charged.
Explanation:
Since the proteins are polymers joined by a big number of amino acids, all the joins occur the same way because in all the amino acids there is always one part that is exactly the same in all of them.
The rest of the molecule in the amino acids, the R group, is different in each one, that is the characteristic of each one, and this is the part that can give the name and some other chemical properties.
Answer:
8%
Explanation:
Given that,
Mass of solute = 8 g
Mass of soultion, (mass of alloy) = 100 g
We need to find the percent by mass of 8.0g copper is added to enough zinc to produce 100g an alloy. It can be calculated by the formula as follows :

So, the percent by mass is 8%.
<span>There are many indicators for predator presence. Some of them are:
Being able to spot predator marks like scratches or fur.
Being able to feel predator movements.
</span><span>Echo-location </span>For example, moths respond to the echo-location calls from their bat predators; moths drop to the ground once they hear the sound pulse from the bat.