Answer:
In first shell 2 electrons are present and 7 electrons are present in last shell
Explanation:
Answer: The correct option is A.
Explanation: The given molecules are the molecules of same element.
These molecules are considered as diatomic species.
Polar molecules are the molecules in which some polarity is present in the bond. These molecules are formed when there is some difference in the electronegativities of the elements. Example: HCl
Non-polar molecules are the molecules where no polarity is present in the bond. These molecules are formed when there is no difference in the electronegativities of the elements. Example: 
The given molecules are non-polar in nature.
Hence, these molecules must be non-polar. So, the correct option is A.
Answer:
A and B is the answer as there structure change
Answer:HNO₃ and NO³⁻ would not function as buffer
Explanation:
The buffer solution are usually prepared by using any weak acid (which would partially dissociate) and mixing this weak acid with its own conjugate base or any weak base (which would partially dissociate) and mixing with with its conjugate acid.
A buffer solution is a solution which resists change in pH of the solution.
Since nitric acid is a very strong acid and hence neither nitric acid HNO₃ or its conjugate base NO³⁻ anionb is suitable for the preparation of buffer solution.
HCO³⁻ is a weak acid and hence it can form a buffer solution with its conjugate base CO₃²-. so they can be used to form buffer.
C₂H₅COOH is a weak acid and hence it can also form buffer solution with its conjugate base.
So only HNO₃and NO³⁻ would not be able to form buffer
So option a is the answer.