Question

Assertion- the formulla unit mass of substance is a sum of the atomic masses of all atoms in formulla used of a compound.
Reason - formula unit mass is calculated in the same manner as we calculate the molecular mass
(A) both A and R are correct ..R is right explanation of A
(B) both A and R are correct. R is not right explanation of A
(C) A is true and R is false
(D) R is true and A is false
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Answer 1

lThe formula mass of a substance is defined as the sum of the atomic masses of constituent atoms in an ionic compound. This is generally used for ionic compounds which do not contain discrete molecules, but ions as their constituent units.