Available Answers

1. 1.

   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)
2. 2.

   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. 

    

3. 3.

   State the differences between Compounds and Mixtures.

4. 4.

   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. 
5. 5.

   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
6. 6.

   Identify the error in the given statements. Circle the incorrect word and write the correct word in the blank. 

   1. Atoms have more than one kind of particles combined together in a fixed ratio by mass.
   2. Noble gases show some properties of metals and some properties of non--metals. 
   3. Molecules consisting of more than three atoms in an element are called polynuclear molecules. 
   4. Sugar solution is a heterogeneous mixture. 
   5. Sublimation is the process of separating a liquid from its solution by evaporating it and then condensing its vapour. 
   6. Oil and water are miscible liquids.