Assertion: There is very little difference in acid strength of \[{{\mathbf{H}}_{\mathbf{3}}}{\mathbf{P}}{{\mathbf{O}}_{\mathbf{4}}},{\text{ }}{{\mathbf{H}}_{\mathbf{3}}}{\mathbf{P}}{{\mathbf{O}}_{{\mathbf{3}}}}\;{\mathbf{and}}\;{{\mathbf{H}}_{\mathbf{3}}}{\mathbf{P}}{{\mathbf{O}}_{\mathbf{2}}}\] ​.
Reason: The hydrogens in these acids are not all bonded to oxygens. The electronegativities of P and H are almost the same.
A.Both Assertion and Reason are correct and reason is the correct explanation for Assertion.
B.Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C.Assertion is correct but Reason is incorrect
D.Assertion is incorrect but Reason is correct
E.Both assertion and reason are incorrect

Hint: To answer this question, recall the concept of acidic strength. Acid strength is defined because the measure of the power of the acid to lose its proton. The more stable the conjugate base or more the difference in electronegativity of the atom attached to hydrogen, the more easily a compound will lose hydrogen ions.

Complete step by step answer:
You are already aware of the term acids. These acids show varied physical and chemical properties of acids. Some simple ones are – they need a pH below 7, they turn blue paper red, they need a sour taste and that they react with alkalis to make salts.
There is little difference of acidic strength among \[{{\mathbf{H}}_{\mathbf{3}}}{\mathbf{P}}{{\mathbf{O}}_{\mathbf{4}}},{\text{ }}{{\mathbf{H}}_{\mathbf{3}}}{\mathbf{P}}{{\mathbf{O}}_{{\mathbf{3}}}}\;{\mathbf{and}}\;{{\mathbf{H}}_{\mathbf{3}}}{\mathbf{P}}{{\mathbf{O}}_{\mathbf{2}}}\] , because the hydrogens in these acids are not all bonded to the oxygen, and phosphorus isn't a highly electronegative element i.e. its oxides are less basic. The electro-negativities of ${\text{P}}$ and ${\text{H}}$ are almost the same so the bond formed is not polar and thus, does not dissociate in water.
Hence, they all have almost similar acidic strength.

Hence, we can say that Both Assertion and Reason are correct and reason is the correct explanation for Assertion.

Therefore, we can conclude that the correct answer to this question is option A.


Note: You ought to remember the difference between strong acids and weak acids: a robust/strong acid is an acid that is $100\% $ ionized in solution but if it is less than $100\% $ ionized in solution, it is a weak base. There are only a few strong acids and certain salts which affect the pH of a solution by changing the acidity or basicity of aqueous solutions by changing the degree of hydrolysis. The general rule is that salts with ions that are a part of strong acids or bases won't hydrolyse, while salts with ions that are a part of weak acids or bases will hydrolyse.