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Ans2
Metalloids are elements which show some properties of metals and some properties of non-metals. Examples: Silicon, boron, arsenic, antimony, germanium, tellurium, polonium.
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Non-metal which exist as a liquid at room temperature is bromine
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The metal that occurs generally in liquid state is Mercury and francium.
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A pure element consist of only one type of atom. A molecule consist of multiple atoms and a compound consists of different atoms. Individually, these are all pure substances. Examples of pure substances include hydrogen, water, silver, 24k gold, sugar, and iron metal.
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- Sugar contains Carbon, hydrogen and oxygen.
- Common salt comprises of sodium and chlorine
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A change in which one or more new substances are formed is known as chemical change. For Example, when the iron is exposed to air and moisture, rust formation takes place. Rust is nothing but Iron Oxide; a new substance formed out of the reaction. ... Hence, rusting of iron is a chemical change.
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The purity of a compound may be checked by determining its melting or boiling point. The technique for determination of melting and boiling points will also be described in this unit. Pure solid and liquid compounds possess sharp melting and boiling points.