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.
The given reaction:
<span>ch3ch2cooh (aq) ↔ ch3ch2coo- (aq) + h+ (aq)
is called a reversible reaction.
This means that, the reaction does not reach an end point.
In this type of reactions, reactants react together to form products, while products combine together to form reactants.
So, the reaction proceeds in both direction forming both reactants and products.</span>
C.
D.
E.
These should be the main reasons. As Pluto was mainly categorized in dwarf planet for not being able to satisfy the last statement which states that it should have a fixed neighbourhood with other planets.
The relation between force and mass and acceleration is

The SI unit will be
Force = Newton
mass =kg
acceleration=
thus

putting values

Thus the acceleration will be

They can all by seperrated or replicated.