Page 60 - Science Class 07

4. An element is a simple form of _____________ .
5. _____________ are those which lack all the metallic a ributes.

6. Atoms of different elements combine to form _____________ .
C. Give reason, why.
1. Elements are called the building blocks of the universe.

2. Metalloids possess the characteris cs of both the metals and non-metals.
3. The mixture of sand and water is called a heterogeneous mixture.
4. We use plus (+) sign between reactants.
D. Very short answer ques ons.

1. What is ma er?
2. What is element?
3. Why metals are called duc le?

4. What are metalloids?
5. What is an atom?
6. What is a molecule?
7. Write the chemical formulae for sulphuric acid and sugar.

8. Balance the following equa ons.
H + O 2H O
2
2
2
Mg + O MgO
2
N + H NH
2 2 3
E. Short answer ques ons.
1. Differen ate between metals and non-metals.
2. Write the conclusion drawn from the Dalton's atomic theory.
3. Differen ate between compounds and molecules.

4. Differen ate between homogeneous mixture and heterogenous mixtue.
5. Write the proper es of mixture.
6. Write any four important proper es of a compound.

7. What do you mean by chemical formula?
8. Describe the process of wri ng chemical equa on with the help of an example.
F. Long answer ques ons.
1. Explain the classifica on of ma er.

2. What do you mean by element? How many elements are known so far.
3. Describe metals with physical proper es.
4. Explain the Dalton’s atomic theory.

5. Write the proper es of mixture.
6. Describe chemical proper es.
7. What are chemical reac ons.

60 Science-7