Question

Non-stoichiometric compounds is/are :

• A. $C{u}_{2}O$
• B. $C{u}_{2}S$
• C. FeO
• D. $H{g}_{2}B{a}_{2}YCaC{u}_2{O}_7$

Answer 1

Answer: (A), (B), (C), (D)

The correct options are
A $C{u}_{2}O$
B $C{u}_{2}S$
C FeO
D $H{g}_{2}B{a}_{2}YCaC{u}_2{O}_7$

Non-stoichiometric compounds are chemical compounds with an elemental composition that cannot be represented by usual integral numbers. They are almost always inorganic compounds and almost invariably solids. In such materials, some small percentage of atoms are missing or too many atoms are packed into an otherwise perfect lattice work. They exhibit special electrical or chemical properties because of these flaws or defects. For example, when atoms are missing, the other atoms can move through the solid more rapidly. Non-stoichiometry is represented by many metal oxides and sulfides. For example, stoichiometric iron(II) oxide, which is rare, has the formula FeO whereas the more common nonstoichiometric material has the formula $F{e}_{0.95}O$. Non-stoichiometric compounds are homogeneous, they are not mixtures. Batteries often rely on materials that can exist in a range of non-stoichiometric states.

Therefore, all given compounds are non-stoichiometric.