In a compound X2O3 the ratio of mass of X to the mass of compound is 7/19 if the atom of element X has a total of 7 neutrons in it's nucleus?

Let y g/mol the molar mass of element X.
Molar mass of O = 16 g/mol

In X₂O₃, the mass ratio of X : O is
2y : 3*16 = 7 : (19 - 7)
2y : 48 = 7 : 12
12*2y = 7*48
24y = 336
y = 14
Molar mass of X = 14 g/mol

mass number of X = 14
(Number of protons in element X) + (Number of neutrons in element X) = 14
(Number of protons in element X) + 7 = 14
Number of protons in element X = 7

Number of electrons in element X = Number of protons in element X = 7
Electron configuration of X : 2, 5
(OR: 1s² 2s² 2p³ for higher class)

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