Q48 of 203 Page 153

If the aluminium salt of an anion X is Al2X3, what is the valency of X? What will be the formula of the magnesium salt of X?

Let the valency of X be y, then 2 x (+3) + 3 x y = 0

So, valency of X = y = -2


As valency of Mg is +2 and that of X is -2 so the formula of Magnesium salt of X will be MgX.


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46

An element A forms an oxide A2O5.

(a) What is the valency of element A?


(b) What will be the formula of chloride of A?

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An element X forms the following compounds with hydrogen, carbon and oxygen:

H2X, CX2, XO2, XO3

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The formula of carbonate of a metal M is M2CO3.

(a) What will be the formula of its iodide?


(b) What will be the formula of its nitride?


(c) What will be the formula of its phosphate?

 50

The atom of an element X contains 17 protons, 17 electrons and 18 neutrons whereas the atom of an element Y contains 11 protons, 11 electrons and 12 neutrons.

(a) What type of ion will be formed by an atom of element X? Write the symbol of ion formed.


(b) What will be the number of (i) protons (ii) electrons, and (iii) neutrons, in the ion formed from X?


(c) What type of ion will be formed by an atom of element Y? Write the symbol of ion formed.


(d) What will be the number of (i) protons (ii) electrons, and (iii) neutrons, in the ion formed from Y?


(e) What is the atomic mas of (i) X, and (ii) Y?


(f) What could the elements X and Y be?