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.
Dmitri Mendeleev
<span> Dmitri Mendeleev and Lothar Meyer individually came up with their own periodic law "when the elements are arranged in order of increasing atomic mass,
certain sets of properties recur periodically.</span>
Answer:
In a parallel circuit, current divides through resistors and current might be different depending upon the resistor and all resistors have the same potential difference. Therefore, if a parallel resistor was removed then the total resistance of the circuit will increase.