Page 45 - NCERT Science Class 10 English Medium

points but gallium and caesium have very low melting points.
These two metals will melt if you keep them on your palm.
(ii) Iodine is a non-metal but it is lustrous.
(iii) Carbon is a non-metal that can exist in different forms. Each
form is called an allotrope. Diamond, an allotrope of carbon, is
the hardest natural substance known and has a very high melting
and boiling point. Graphite, another allotrope of carbon, is a
conductor of electricity.
(iv) Alkali metals (lithium, sodium, potassium) are so soft that they
can be cut with a knife. They have low densities and low melting
points.
Elements can be more clearly classified as metals and non-metals
on the basis of their chemical properties.

Activity 3.8
Activity 3.83.8
Activity 3.8
Activity 3.8
Activity
n Take a magnesium ribbon and some sulphur powder.
n Burn the magnesium ribbon. Collect the ashes formed and dissolve
them in water.
n Test the resultant solution with both red and blue litmus paper.
n Is the product formed on burning magnesium acidic or basic?
n Now burn sulphur powder. Place a test tube over the burning
sulphur to collect the fumes produced.
n Add some water to the above test tube and shake.
n Test this solution with blue and red litmus paper.
n Is the product formed on burning sulphur acidic or basic?
n Can you write equations for these reactions?

Most non-metals produce acidic oxides when dissolve in water. On
the other hand, most metals, give rise to basic oxides. You will be learning
more about these metal oxides in the next section.

Q U E S T I O N S

1. Give an example of a metal which
(i) is a liquid at room temperature.
(ii) can be easily cut with a knife. ?
(iii) is the best conductor of heat.
(iv) is a poor conductor of heat.
2. Explain the meanings of malleable and ductile.

3.2 CHEMICCHEMICAL PROPERTIES OF METAL PROPERTIES OF METALSALS
3.2 CHEMICAL PROPERTIES OF METAL PROPERTIES OF METALSALS
3.2 CHEMICAL PROPERTIES OF METALS
3.2 CHEMIC
3.2
We will learn about the chemical properties of metals in the following
Sections 3.2.1 to 3.2.4. For this, collect the samples of following metals –
aluminium, copper, iron, lead, magnesium, zinc and sodium.

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