Elements, Compounds And Mixtures

Question 1

Element

Answer 1

Any pure substance which cannot be broken into two or more pure substances by any chemical means.

Question 2

Noble Gases

Answer 2

The elements found in air in traces in gaseous state,which do not react chemically with any other element.

Question 3

Atom

Answer 3

The smallest particle of an element, which may or may not have independent existence but always take part in a chemical reaction.

Question 4

Molecule

Answer 4

The smallest unit of a pure substance which always exists independently and can retain all the chemical and physical properties of that substance.

Question 5

Compound

Answer 5

When the molecule of a pure substance contains two or more atoms of different elements combined together in a definite ratio, then it is said to be a molecule of a compound.

Question 6

Formula

Answer 6

A symbol representation of one molecule of a compound representing the number of atoms of various elements present in it.

Question 7

Pure substance

Answer 7

A homogeneous material which contains particles of one kind and has a definite set of properties. However, if a substances made of two or more kinds of particles, combined together, then the proportion of these combining particles by weight must remain constant.

Question 8

Mixture

Answer 8

If two or more substances are mixed together in any proportion, such that they do not undergo any chemical change, but retain their individual properties.

Question 9

Alloy

Answer 9

The homogeneous mixture of molten metals on cooling forms a solid.