Question

$ 0.98\text{ }g $ of an acid (A) of phosphorus in $ 100\text{ }mL $ solution is $ 0.1\text{ }M $ and neutralizes $ 300 $ mL of $ 0.1\text{ }N\text{ }NaOH $
 $ \left( A \right){\xrightarrow{\mathop{MgCl_2}}}\,\left( B \right){\xrightarrow{\mathop{\Delta}}}\,\left( C \right) $
If $ 1.11 $ of $ \left( C \right) $ is obtained from given $ \left( A \right). $ Compounds (A), (B) and (C) are identified as: $ A:{{H}_{3}}P{{O}_{4}},\text{ }B:MgHP{{O}_{4}} $ ​ and $ C:M{{g}_{2}}{{P}_{2}}{{O}_{7}} $
​If true enter $ 1 $ , else enter $ 0. $

Answer 1

Hint :We know that the oxidation number of an atom is the charge that results when the electrons in a covalent bond are assigned to the more electronegative atom. Oxidation state and oxidation number are quantities that commonly equal the same value for atoms in a molecule and are often used interchangeably.

Complete Step By Step Answer:
Let X be the molar mass of acid of phosphorus. The product of the molar mass and molarity is the amount in $ g/L. $
 $ \therefore X\text{ }molarity=\text{ }g/L $
Hence, $ X\text{ }0.1=\text{ }9.8g{{L}^{-1}} $
Molar mass of acid $ =\text{ }98\text{ }g\text{ }mo{{l}^{~-1}}, $ Let basicity of acid be $ =\text{ }x, $ by converting the molarity of acid in normality of acid then $ 0.1 $ M acid $ =\left( 0.1\text{ }X\text{ } \right)\times N $
The amount of acid present is equal to the amount of the base neutralized.
 $ 100\times \text{ }0.1\text{ }XX=300X\left( 0.1\text{ }N\text{ }NaOH \right) $ , Since we know that basicity $ x=3 $
Thus, acid is tribasic which is phosphoric acid., $ {{H}_{3}}P{{O}_{4}} $ .
Hence, the compound A is $ {{H}_{3}}P{{O}_{4}} $
The compound B is $ MgHP{{O}_{4}} $
The compound C is $ M{{g}_{2}}{{P}_{2}}{{O}_{7}} $
Now we just have to identify if C is confirmed by the following reaction: $ 2{{H}_{3}}P{{O}_{4}}\xrightarrow{{}}M{{g}_{2}}{{P}_{2}}{{O}_{7}} $
 $ 2 $ moles of A gives One mole of C.
Hence, $ 0.98\text{ }g $ of A will give $ 1.11\text{ }g $ of C.
Correct answer is 1.

Additional Information:
Most of the time, it doesn't matter if the term oxidation state or oxidation number is used. Oxidation state refers to the degree of oxidation of an atom in a molecule. Oxidation states are typically represented by integers, which can be positive, negative, or zero. In some cases, the average oxidation state of an element is a fraction, such as $ 8/3 $ for iron in magnetite

Note :
Remember that Phosphorus belongs to the group $ 15. $ It has $ 5 $ electrons in its valence shell. So it can either lose $ 5\text{ }e\text{ }- $ to attain +5 oxidation state or gain $ 3\text{ }e- $ to attain $ -3 $ oxidation state. Hence its oxidation state varies from $ -3 $ into $ +5 $ in $ {{H}_{3}}P{{O}_{4}}. $