C. Groups 13-16 contain metalloids.
If you look on a periodic table, these usually have a different color.
I believe the answer is C) there is an obvious reasoning for this all you have to do is eliminate answers that don't seem right for example, A)the plates are all moving the same direction every plate moves in different directions. B) The plates are all the same size. Well, it's really obvious that that is not true because every plate has its different shape and size. D) where two plates meet, they always move apart. If this were true, then we would never have earthquakes when plates meet earthquakes happen. so there for the answer is C)
Answer: a) 
b) 
c) 
d) 
e) 
Explanation:
A balanced nuclear equation is one in which the atomic number and mass number remains same on both sides of the equation i.e the number of protons and neutrons remain same.
General representation of an element is given as:
Z represents Atomic number
A represents Mass number
X represents the symbol of an element
a) 
b) 
c) 
d) 
e) 
<span>Too much B. potassium can
slow and eventually stop the heart, and supplements should be taken only
under the care of a physician.
</span>
Answer:

Explanation:
10.11 g sample of
contains 22.34%
by mass
According to the law of constant composition the if one sample of
has 22.34% of
by mass then any other sample of
will have the same percentage of the amount of
.
For a sample of 7.09 g we have

The mass of sodium in the required sample is
.