Question

A, E, M and n are the atomic weight, equivalent weight, molecular weight and valency of an element. The correct relation is:
A. A=E*n
B. A=M/E
C. A=M/n
D. M=A*n

Answer 1

Hint: we know that avagadro’s law explains that equal volumes of all gases contain equal numbers of molecules under similar conditions. Now since one mole molecules of all gases contain the same number of molecules therefore they occupy the same molecules under STP. Hence we can find a relation to the following terms listed above.

Complete step by step solution:
Let us define the terms above atomic weight is the mass of one mole atom of any element or it can be derived by weight of the substance /number of moles of the substance. Equivalent weight is the weight of the solute to the number of the gram equivalents of solute. Molecular weight is a concept similar to atomic weight. It is the mass of one mole of molecules of any element. Valency of n-factors are defined differently to acids, bases and redox or non redox reactions.

From the law of gram equivalents the number of gram equivalents of all reactants is equal to each other in a reaction. Let us find out the relation between all the terms,
 $
  A/M = \dfrac{{weight}}{{number \, of \, moles}} \\
  E = \dfrac{M}{{n}} = \dfrac{A}{{n}} \\
  E*n = A \\
 $
We can write the equivalent weight in the terms of molecular weight using n factor and since atomic weight is similar to molecular weight we can derive to such conclusions.

Hence from the above equations we understand the relation between the terms. Let us understand the different values of n-factor in different cases:
i) acids: the number of moles of protons replaced per mole of the acid.
ii) bases: the number of replaceable hydroxide ions per mole of the base.
Iii) redox reactions: number of moles of electrons lost or gained pr mole.

Hence the correct option is A.

Note:
Whenever two substances react such that their ‘n ’ factors are in the ratio of x:y,the molar ratio of these substances in balanced chemical reaction would be in the ratio y:x. it can also be understood from above that number of gram equivalents of a substance=n*number of moles.