There are three substances X, Y and Z. The substance X does not have a fixed melting point or boiling point and it still shows the inpidual properties of its constituents. The substance Y is a pure substance which occurs in nature as such. The substance Y has a fixed melting point and boiling point but it cannot be broken down into simpler substances by any chemical means. The substance Z is also a pure substance whose properties are entirely different from those of its constituents. The substance Z can however, be divided by electrolysis into two substances which belong to the same class of substances as Y.(a) What type of substance could X be? Name one substance like X.(b) What type of substance could Y be? Name one substance like Y.(c) What type of substance could Z be? Name one substance like Z.(d) Which process involves absorption or release of an appreciable amount of energy : formation of substance X or formation of substance Z?(e) Name the three groups into which all the substances like Y are divided on the basis of their properties.
(a) Substance X is a mixture as it does not have a fixed melting or boiling point. Moreover, it shows the properties of its constituents.
Sugar solution in water is a substance like X.
(b) Substance Y is an element as it has a fixed melting or boiling point but it cannot be split into simpler substances by chemical processes.
Hydrogen is a substance like Y.
(c) Substance Z is also a pure substance whose properties are entirely different from those of its constituents. Hence, it must be a compound.
Sugar is a substance like Z.
(d) Formation of Z (a compound) involves absorption or release of an appreciable amount of energy.
(e) The three groups are metals, non-metals and metalloids. All the substances like Y are divided into these groups on the basis of their properties.
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