Answer:
A. 3 x 10-12
Explanation:
Generally, the parts-per notation is used to represent very small concentration without any specific unit.
Parts per million is notated as 
Parts per billion is notated as 
Parts per trillion is notated as 
Hence, 3 parts per trillion will be written as 3 x
The correct option is A.
when liquid water changes into solid ice, it increases in mass
The answer is B. Below freezing
Hey there!:
H is always +1 so the H's have a +3 charge.
O is always -2 so the O's have a -8 charge .
Now, suppose oxidation state for P = X , then :
+3 + X + (-8) = 0 (because of neutral molecule)
x = 8 - 3
x = + 5
So, X = +5 oxidation state.
Answer C
Hope that helps!
