Write/Choose the correct answer. 

1. ______ are represented by chemical formulae.
2. Atoms of the same of different elements can join together to form molecules. (True/False)
3. Can an atom of hydrogen exist independently? If not, then how does it exist?
4. Phosphorus contains _____ atoms in molecule. 
5. Molecular formula gives the number of atoms of each kind of element present in one molecule of a compound. (True/false)

Write/Choose the correct number. 

1. A pure substance has definite physical and chemical properties. (True/False)
2. _____ are physical combinations of two or more elements or compounds in any proportion. 
3. Salt solution is a (homogeneous/heterogenous) mixture. 
4. A heterogenous mixture does not have the same properties throughout its bulk. ( True/False)
5. Blood is a ______ mixture. 

State the differences between Compounds and Mixtures.

Write/Choose the correct answer. 

1. A mixture of two miscible liquids is separated by ________.
2. A mixture of kerosene and water can be separated by using a separating funnel. ( True/False)
3. Liquids which do not mix with each other and form separate layers are called ________.
4. Fractional distillation is based on different freezing points of liquids. (True/False)
5. Boiling a liquid removes dissolved gas. (True/False)
6. The technique of ______ is based on the principle of selective adsoprtion. 

Answer in one word/ a few words. 

1. The simplest form of a pure substance made up of only one kind of atom. 
2. A pure substance formed when atoms or molecules of different elements combine. 
3. The number of atoms contained in a molecule of an element. 
4. A substance that is a combination of two or more elements or compounds. 
5. A homogeneous mixture of solvent and solute. 
6. The process by which a liquid is converted into its vapour state