1. Classify the following into compounds and elements :
(a) HCI
(b) N2
(c) 03
(d) Co
2. Select four elements from the following list :
Urea, irqu, sulphur, chalk, ozone, osmium, carbon, carbon monoxide, saw dust, suga
3. Define and illustrate pure substance.
4. What are different types of pure substance. Give two examples of each.
5. Why air is called a mixture ?
6. Explain : Water is a compound.
7. Why is copper called a metal ?
8. Graphite is used for making electrodes. Why?
9. How many types of mixtures are known ? Give one example of each type.
10. A given sample is pure water. How it can be verified ?
11. Define and illustrate chemical change.
12. Discuss types of solutions with examples ?
13. How is a mixture of the miscible liquids separated ?
Answers
Answer:
1.]
Compounds:
a.) HCl
d.) CO
Elements:
b.) N2
c.) O3
2.]
Sulphur, Osmium, Ozone, Carbon
3.]
Pure Substance:
The substance which is made up of one type of particle .
4.]
Elements, Compound
5.]
Air is a mixture because I air there are many gases like Nitrogen, Oxygen, etc. They are not chemically mixed.
6.]
Compounds contain two or more different elements. Water is a molecule because it is made it contains molecular bonds. Water is also a compound because it is made from more than one kind of element (Hydrogen, Oxygen)
7.]
Copper is a mineral and an element essential to our everyday lives. It is a major industrial metal because of its high ductility, malleability, thermal and electrical conductivity and resistance to corrosion.
8.]
Because Graphite is a good conductor of electricity.
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