CBSE Class 10 Science 2017 · Paper 31/1/C · Question 14

Metals and Non-metals 3 marks Medium

An element ‘X’ with electronic configuration (2, 8, 2) combines separately with two radicals,

(NO_{3})^{-}

and

(SO_{4})^{2 -}

(i)Is ‘X’ a metal or a non-metal ? Write the nature of its oxide.
(ii)Write the formula of the compounds of ‘X’ formed by the combination of these radicals. Are these compounds covalent or electrovalent ?

Answer

X is a metal with a basic oxide; its compounds $X(NO_{3})_{2}$ and $XSO_{4}$ are electrovalent.

(i) X is a metal: its atom has only two electrons in the outermost shell and gives them up to form the ion

X^{2 +}

(with 12 electrons in all, X is magnesium). Its oxide, XO, is basic. (ii) With the nitrate radical X forms

X(NO_{3})_{2}

, and with the sulphate radical it forms

XSO_{4}

. Both are electrovalent (ionic) compounds, made of

X^{2 +}

ions and negatively charged radicals held together by electrostatic attraction.

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