Chapter 2 Metals and Non – Metals
* Short Answer type questions:
Q. 1. What is malleability ?
Ans The property of metals by which they can be beaten into thin sheets is called malleability.
Q. 2. What is alloys ?
Ans Alloys are homogeneous solid mixtures of metals, or of metals and non-metals in definite proportion.
Q. 3. What is melting point of a substance ?
Ans The temperature at which any solid substance is converted into liquid state, is known as melting point of that substance. Eg. – the melting point of iron is 1593 °C.
Q. 4. Graphite is good conductor of electricity. Why?
Ans Non- metals are poor conductor of electricity because they do not have free electrones. But graphite is exception because it has free electrons for movement So grappite is a good conductor of electricity.
Q. 5. Why does the syrup of lemon not stored in iron pot ?
Ans Lemon juice is acidic in nature. Acidic materials are not kept in iron container because acid and iron react togethet to form poisonous substance which is injurious for health.
* Long Answer type questions : —
Q. 1. Why does sodium metal store under kerosene oil ?
Ans Sodium metal is highly reactive metal. If it reacts vigorously with oxygen and water and produce sodium hydroxide or hydrogen gas which catches fire. To protect sodium from air it is stored under kerosene.
Q. 2. Differentiate metals and non-metals on the basis of physical properties.
Property Metals Non-metals
1. Appearancé, Lusturous, Non- lusturous
2. Hardness, Solid at room
temperature, Liquid and gas at room temperature
3. Malleable, Metals are malleable, Non-metals are not malleable.
4. Ductility, Metals are ductile, Non-melals are not ductile
5. Heat conduction, It conducts heat, It do not conducts heat
6. Electricity conduction, It conducts electricity, It do not conduct electricity
Q. 3. Write any four uses of metals.
Ans Uses of metals are:
1. Metals are used in making utensils.
2. Copper wires are used in electrical spparatus, radio, electrical wires fridge etc.
3. Aluminium and iron sheets are used to protect our home from sunlight and rain .
4. Gold, silver and tin are used in making ornaments and coins.
5. Mercury is used in thermometer.
Q. 4. Copper wire is used in electric wiring of home. Why?
Ans Metals are good conductor of heat and electricity. Silver is the best conductor of electricity. Silver is expensive metal, hence it is not generally used but copper is good conductor and there is less wastage of energy. Therefore, copper is used in electric wiring of houses.
Q.5. Differentiate metals and non-metals on the basis of chemical properties Properties.
* Properties :–
1. Reaction with Air :–
Metals react with oxygen and form basis oxides. Magnesium(Mg)+Oxygen(O2) :– Magnesium oxide(MgO)
* Non – metals
Non metals react with air and form non – metalic oxides which are acidic in nature. Sulphur ( S ) + Oxygen ( O2 ):– Sulphur dioxide (SO2).
2 Reaction with Water :–
Metals react with water and form metallic hydroxide andrelease hydrogen gas. Sodium (Na) + water (H2O). sodium hydroxide (NaOH) + hydrogen ( H2 )
* Non- metals
Non – metals do not react with water.
3. Reaction with Acid :–
Metals react with acid and release hydrogen gas. Cu + H2S04 – Cu So4 + H2
* Non – metals
Most of the non – metals do not react with dilute acids.