# An element 7A14 exists as diatomic gas in nature which is relatively inert and forms 78% of earth’s atmosphere.

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An element 7A14 exists as diatomic gas in nature which is relatively inert and forms 78% of earth’s atmosphere.

(a) Identify the gas and write its molecular formula. Write the formulae of its nitrite and nitrate ions.

(b) How many moles of this gas would contain 12.044 × 1023atoms of this element? (Avogadro’s no. = 6.022 × 1023

(c) Calculate the molecular mass of

(i) NH4 NO3 and                   (ii) HNO

(Given atomic masses N = 14 u, O = 16 u, H = 1u)

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(a) Element A has atomic number 7 so it is Nitrogen gas (N2

Formulae: Nitrite ion (No2

Nitrate ion (No3

(b) 1 mole of N2 gas = 6.022 × 1023 molecules of N

= 12.044 × 1023 atoms of N

(c) (i) Molecular mass of NH4 NO

= 14 + 1 × 4 + 14 + 3 × 16

= 80 u

(ii) Molecular mass of HNO3

= 1 + 14 + 3 × 16

= 63 u

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