Statement I: Formula unit mass is used to calculate the mass of ionic compounds.

Statement II: Formula unit mass is calculated by adding the atomic masses of all the ions involved in the compound.

Only statement I is true

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Only statement II is true

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Both statements are true

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Both statements are false

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Solution

The correct option is C Both statements are true
Formula unit mass is used to calculate the mass of ionic compounds. It is the sum of the atomic masses of all the ions in the compound.

For example, ${MgCl}_{2}$ is an ionic compound formed by the ions $M g^{2 +}$ and $C l^{-}$ .

The formula unit mass of ${MgCl}_{2}$ = atomic mass of Mg + (2 $\times$ atomic mass of Cl) = 24 + (2 $\times$ 35.5) = 95 u.

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Similar questions

Q. (a) Define 'formula unit' of an ionic compound. What is the formula unit of (i) sodium chloride, and (ii) magnesium chloride ?
(b) Calculate he formula masses of the following compounds :
(i) Calcium chloride
(ii) Sodium carbonate
(Given : Atomic masses : Ca = 40 u ; Cl = 35.5 u ; Na = 23 u ; C = 12 u ; O = 16 u)

Q. Statement I: Two atoms of X combine with three atoms of Y to form

X_{2} Y_{3}

.

Statement II: From the chemical formula of the compound

X_{2} Y_{3}

, we can conclude that the valency of X is 2.

Choose the incorrect statement/statements from the following:

(i) Atomic mass of hydrogen is 1 u.
(ii) Atomic mass of helium is 2 u.
(iii) Atomic mass of chlorine is 17 u.
(iv) Atomic mass of phosphorous is 31 u.

Statement I: Power = $\frac{V^{2}}{R}$ is used only when the potential difference across the resistors are constant.

Statement II: Power = $I^{2}$ R is used only when current in the resistors are constant.

Q. Statement I

P b^{4 +}

compounds are stronger oxidising agents than

S n^{4 +}

compounds.
Statement II The higher oxidation states for the group 14 elements are more stable for the heavier members of the group due to 'inert pair effect'.(J2008,3M)

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Statement I: Formula unit mass is used to calculate the mass of ionic compounds. Statement II: Formula unit mass is calculated by adding the atomic masses of all the ions involved in the compound.

Statement I: Formula unit mass is used to calculate the mass of ionic compounds.

Statement II: Formula unit mass is calculated by adding the atomic masses of all the ions involved in the compound.