Materials: Metals and Non Metals Class 8 Extra Questions and Answers

These AP 8th Class Physics Important Questions and 6th Lesson Materials: Metals and Non Metals Class 8 Extra Questions will help students prepare well for the exams.

Class 8 Science Materials: Metals and Non Metals Extra Questions

Materials: Metals and Non Metals Class 8 Important Questions

Question 1.
Name some common metals.
Answer:
Iron, copper, aluminium, zinc, nickel, mercury, silver and gold.

Question 2.
Name some common non-metals.
Answer:
Carbon, chlorine, nitrogen, oxygen, sulphur, iodine.

Question 3.
Metals are hard to cut except two metals. Name such metals.
Answer:
Sodium and potassium.

Question 4.
Name the property to the metals by virtue of which these can be beaten into sheets.
Answer:
Malleability.

Question 5.
Giving examles, explain the term ‘malleability’.
Answer:
Malleability is a property of beating a metal into sheets. For example, if you take a piece of any metal – iron, copper, zinc or aluminium, and beat it with a hammer, it becomes longer and larger and does not break. Thus, metals can be obtained as thin sheets.

Question 6.
Non – metals do not conduct heat or electricity except one. Name the non-metal.
Answer:
Carbon is the non-metal and it conducts heat and electricity as graphite.

Question 7.
Name two non-metals which are soft solids.
Answer:
Sulphate and iodine are soft solids.

Question 8.
Name the property of the metals by virtue of which it can be drawn into wires.
Answer:
Ductility.

Question 9.
What do you mean by ductility ? Which substance show this property ?
Answer:
The property which allows a substance to be drawn into wires is called ductility. Metals show ductility. For example, copper, aluminium and iron can be drawn into wires when hot.

Question 10.
If you put one end of a rod of a metal in hot water, you feel hot at the other end. What does it mean ? What is this property of metals called ?
Answer:
The above observation means that heat is transmitted from one end to the other. This property of metals is called conductivity.

Question 11.
Of following metals and non-metals which occur in liquid state at ordinary temperature ?
Copper, Aluminium Mercury, Iodine, Sulphur, Bromine.
Answer:
Mercury – Metal
Bromine – Non – metal

Question 12.
Name one non-metal which has metallic lustre.
Answer:
Iodine.

Question 13.
Which property of metals make them useful as ringing bells ?
Answer:
Sonority.

Question 14.
What do you mean by Sonority ?
Answer:
Since metals produce ringing sounds, they are said to be sonorous and this property of metals is called sonority.

Question 15.
Why cannot you have wooden bells ?
Answer:
Since wood is a non-metal and hence, it cannot produce ringing sound. Only metals can produce ringing sounds.

Question 16.
What makes aluminium useful for wrapping of food items ?
Answer:
Aluminium can be converted into thin sheets which can be folded into any shape while wrapping of food items. It is readily available at affordable cost.

Question 17.
Name some physical properties of metals.
Answer:
Metals are generally solid, hard, ductile, malleable, which have metallic luster they are sonorous and good conductors of heat and electricity.

Question 18.
What are the elements called which can neigher fit with metals or non metals ?
Answer:
Metallioids.

Question 19.
Name some metalloids.
Answer:
Arsenic, antimony, silicon and germanium.

Question 20.
What happens when you hammer a metal and a non-metal ?
Answer:
When a metal is hammered it is converted into sheets. When a non- metal is hammered, it breaks away easily.

Question 21.
Some non metals like phosphorus are kept in water to protect them from atmospheric oxygen. State the property of the non-metals utilised here.
Answer:
Non-metals do not react with water.

Question 22.
What do you mean by displacement reactions ?
Answer:
In a displacement reactions, a more reactive metal can replace (or displace) a less reactive metal from the solution of its salt.

Question 23.
What would you observe when a strip of zinc is dipped in the solution of copper
sulphate ?
Answer:
It will be observed that blue colour of the copper sulphate solution starts fading and zinc strip gets a shiny brown coating of copper.

Question 24.
Can copper displace iron from iron sulphate solution ? Give reasons.
Answer:
No, because copper is less reactive than iron. It is only more reactive metal that displaces a less reactive metal from its compound in aqueous solution.

Question 25.
Iron gets rusted when exposed to air and moisture for a long time. State the physical and chemical nature of the substance formed.
Answer:
Substance formed when iron is exposed to air and moisture for a long time is called rusting. It is a brown powder and basic in nature.

Question 26.
A substance was burnt in air. The white reside obtained was added to water. This water solution turned red litmus into blue. State whether the substance is a metal or a non-metal.
Answer:
Metal.

Question 27.
A purple coloured non-metal forms a brown solution in alcohol which is applied an wounds as an antiseptic. Name the non-metal.
Answer:
Iodine.

Question 28.
Zinc sulphate forms a colourless solution in water. Will you obseve any colour on adding copper, turning in it ?
Answer:
No, because displacement reaction does not place.

Question 29.
Which of the following metals can displace the other two metals from their salt solution ?
Zinc, Iron, Copper.
Answer:
Zinc.

Question 30.
Arrange the following metals in the order of their decreasing chemical activity : magnesium, potassium, iron, gold.
Answer:
Potassium > Magnesium > Iron > Gold.

Question 31.
Which non-metal is essential for our life and-all living beings inhale it during breathing ?
Answer:
Oxygen gas.

Question 32.
Name two major non-metals which are present in fertilisers and enhance the growth of plants.
Answer:

1. Nitrogen,
2. Phosphorus.

Question 33.
Which non-metal is used to disinfect water ?
Answer:
Chlorine.

Question 34.
Name the metals which air used to make ornaments.
Answer:

1. Gold
2. Silver.

Question 35.
Name the common non-metals that are used in our daily life directly or indirectly.
Answer:
Oxygen, nitrogen, chlorine, sulphur and iodine.

Question 36.
Explain the use of chlorine in water purification plants.
Answer:
Chlorine has the ability to kill germs. Hence, it is used in water purification plants.

Question 37.
Name the metal that is found in liquid state at room temperature.
Answer:
Mercury.

Question 38.
How are metal oxides formed ?
Answer:
Metal oxides are formed when metals react with oxygen.

Question 39.
Why is immersion rod used for heating liquids made of metallic substances ?
Answer:
It is because metallic substances are good conductors of electricity.

Question 40.
What happens when a solution of metal oxide is tested with i) blue litmus, ii) red litmus ?
Answer:

1. GimNo change in the colour of blue litmus,
2. The red litmus changes into colour.

Question 41.
If a blacksmith beats an iron piece with hammer, do you think, it will change its shape ? If yes would you expect a similar change in wood log on beating ?
Answer:
Yes, iron piece will change its shape as it is a metal. It increases in size and does not break. If a wood log is beaten it does not change its shape but it breaks into pieces.

Question 42.
Copper is used to make electric wires, why ?
Answer:
Copper is a good conductor of electricity, so electric wires are made up of copper.

Question 43.
Which type of materials we used for making fine electrical contacts in super computers and solar cells ?
Answer:
We use gold and silver metals for making fine electrical contacts in super computers and solar cells.

Question 44.
Iron metal reacts slowly with the oxygen and moisture of damp air to form rust. What is the rust chemically known ? State whether the rust formed is acidic, basic or neutral.
Answer:
Rust is iron (III) oxide (Fe₂O₃)
Rust is basic oxide

Question 45.
Which liquid metal is used for making thermometers ?
Answer:
Mercury metal is used for making thermometers.

Question 46.
Name the metal
a) which reacts with dilute hydrochloric acid to produce hydrogen gas.
b) which does not react with dilute hydrochloric acid.
Answer:
a) Zinc metal
b) Copper metal

Question 47.
A doctor prescribed a tablet to patient suffering from iron deficiency. The tablet does not look like iron. Explain.
Answer:
Iron is a metal but the tablet is not made up of iron metal. It is made up of a salt of iron. So, it does not look like iron.

Materials: Metals and Non Metals Extra Questions

Question 1.
Sudha bought a statue made up of copper. To her surprise, it acquired a dull green coating after a couple of months. Explain the reason.
Answer:
The green material is a mixture of coper hydroxide (Cu(OH₂)) and copper carbonate (CuCO₃) formed due to the reaction of copper with moist air. The following is the reaction.

Question 2.
We should not store food stuff in container which is made up of metals such as copper, zinc, aluminium etc. Why ?
Answer:
Some food stuffs which have acidic nature such as citrus fruits, lemon pickles and curd should not be stored in container made up of metals such as copper, zinc, aluminium andiiron. This is because acid present in food stuff reacts with these metals to produce toxic compounds which cause food poisoning.

Question 3.
Aluminium is a highly reactive metal, yet it is used to make utensils for cooking. Give reason.
Answer:
Aluminium is a good conductor of electricity. When it is exposed to air its surface gets covered with thin layer of oxides which prevents metal underneath from further corrosion.

Question 4.
In what form magnesium is found in plants ?
Answer:
Magnesium is found in plants in the form of ionic salts in chlorophyll. Due to its deficiency, plants are unable to produce enough chlorophyll and as a result, leaves develop yellowish colour.

Question 5.
The doctor reported iron deficiency in the body. Where is iron present in our body?
Answer:
Iron is present in our body. Red Blood Cells (RBCs) of blood contain a respiratory pigment known as haemoglobin. Each molecule of haemoglobin contains iron atom as its important component.

Question 6.
Compare the properties of metals and non-metals with respect to malleability, ductility and conductivity.
Answer:

Metals	Non-metals
1. Malleable – give sheets on hammering.	1. Brittle – no sheets can be obtained.
2. Ductile – can be transformed into obtained.	2. Not ductile – no wires can be wires.
3. Good conductors of heat and electricity.	3. Bad conductor of heat and electricity.

Question 7.
A more reactive metal displaces the less reactive metal from its salt solution. What do you mean by this reaction ?
Answer:
In a chemical reaction, when a more reactive metal displaces the less reactive metal from its salt solution, it is called displacement reaction, e.g. zinc can displace copper from its copper sulphate solution as zinc is more reactive than copper.

Less reactive metal cannot displace the more reactive metal from its salt solution e.g. copper cannot displace zinc from its solution zinc sulphate as copper is less reactive than zinc.

Question 8.
Discuss all the physical properties of metals.
Answer:
Physical properties of metals.

1. Metals are good conductors of heat and electricity.
2. Metals are malleable and ductile.
3. They are lustrous and can be polished.
4. Generally they are solid at room temperature except mercury.
5. Metals generally have high melting and boiling points.

Question 9.
Take a piece of burning charcoal and collect the gas evolve in a test – tube.
(i) Find the natural of gas.
(ii) Write down equations of all the reactions taking place in this process.
Answer:
(i) Charcoal produces carbon dioxide on burning. This gas turns lime water milky and its solution turn blue litmus to red.
Hence, it is acidic.

Question 10.
(i) Why does an aluminium vessel lose its shining soon after use ?
(ii) Can we store lemon pickle in an aluminium utensils ? Explain
Answer:
(i) Aluminium is a reactive metal. As it comes in an contact with air, it forms a dull layer of aluminium oxide on its surface and hence loses its shine.
(ii) No, we cannot store the lemon pickle in aluminium utensils because aluminium is a metal and lemon is acidic. The acid reacts with metal to give hydrogen which would spoil the food and make it unfit to use.

Question 11.
Sodium metal is kept in kerosene but hot in water. Why ?
Answer:
Sodium metal is highly reactive metal, when exposed in air, it starts to burn to form oxide. In the same way, it forms hydroxide with water. It does not react with kerosene. So, to present it, it is kept in kerosene not in water.

Question 12.
What happens when magnesium rihbon is burnt in air ? How will you test for its acidic / basic nature ?
Answer:
A white coloured ash of magnesium oxide is obtained on burning ribbon. When white ash (Magnesium oxide) is dissolved, on testing, it turns red litmus paper to blue. Hence, it is basic in nature.
2 Mg + O₂ → 2 MgO

Question 13.
Imagine the human life without metals, write briefly about the consequences.
Answer:

1. There would not be any utensil for Cooking.
2. There would not be trains, buses, aeroplanes for travelling.
3. There would be school bells, no agricultural material, no electrical appliances, no automobiles, no satellites, nomachinery and no decorative materials.
   So everything in life direclty or indirectly depends upon metals. So we cannot imagine a life without metals.

Question 14.
After completion of metals and non-metals chapter, Raheem understood that metals are hard and non-metal are soft. During the discussion with his brother he came to know that diamond is a hardest material and it is a non-metal. Similarly mercury is a soft material and it is a metal. These findings from the discussion raised some questions in Raheem’s mind. Can you guess those questions ? Write them.
Answer:
The doubts arised in Raheem’s mind are

1. If diamond is hard how it behave like a non-metal ?
2. If mercury is soft material then how it acts as metal ?
3. What are the properties which actually decide whether given material is either metal or non-metals.

Question 15.
How is malleability of metals used in our daily life ?
Answer:
Metals can be flattened into sheets is called malleability. Due to this metals can be made into different shapes like railway coaches, railway tracks, cooking utensils, etc. So malleability of metals is extremely useful in daily life.

Extra Questions of Materials: Metals and Non Metals Class 8

Question 1.
Discuss all the chemical properties of (a) Metal and (b) Non-metals.
Answer:
(a) Chemical properties of metals :
i) Metals react with oxygen to produce oxides with are alkaline in nature.
E.g:

ii) Metallic oxides produce bases by reacting with water differently.

iii) Metals react with acid to produce hydrogen gas.

iv) More reactive metals displace the less reactive metals from their compounds in an aqueous solution.

(b) Chemical properties of Non-metals :
i) Non-metals react with oxygen to produce oxides which are acidic in nature.

Sulphur dioxide Water Sulphurous acid
ii) Non-metals do not react with water.
iii) Non-metals do not show displacement reactions.

Question 2.
Write the difference between metals and non – metals on the basis of their physical properties.
Answer:

Metals	Non-metals
1. Metals are good conductors of heat and electricity.	Non-metals are poor conductors of heat and electricity.
2. Metals are malleable and ductile.	Non-metals are neither malleable nor ductile.
3. Metals are lustrous and can be polished.	Non-metals are non-lustrous and cannot be polished.
4. Metals are solids except mercury.	Non-metals can exist in all states
5. Metals have generally high melting and boiling points.	Non-metals generally have low melting and boiling points.

Question 3.
Write three important uses of non-metals.
Answer:
Important uses of non-metals.

1. Non-metals are essential for our life as all living beings inhale oxygen and breath out carbon dioxide during breathing.
2. They are used in fertilizers to enhance the growth of plants.
3. Non-metal is used in the purple coloured solution that is applied on wounds as an antiseptic.
4. Non-metals are used in crackers.

Question 4.
How are acids and bases formed?
Answer:
Acids : Acids are formed when non-metals react with oxygen and form non -metallic oxides. These oxides when dissolved in water, form acids.
E.g:

Bases : Bases are formed when metals react with oxygen and form metallic oxides. These oxides when dissolved in water, form bases.
E.g:

Question 5.
State some chemical properties on the basis of which metals can be distinguished from non-metals.
Answer:

Metals	Non – metals
1. Metals from basic oxides with oxygen which turn red litmus into blue. 2 Zn + O2 → 2 ZnO	1. Non-metals from acidic oxides with oxygen which turn blue litmus into red. S + O2 → SO2
2. Metals react with dilute acids to form salt and hydrogen gas Mg + 2 HCl → MgCl2 + H2	2. Non-metals do hot react and if react then they form corresponding acids S + 6 HNO3 → H2SO4 + 6 NO2 + 2 H2O
3. Metals are electropositive in nature.	3. Non- metals are electronegative in nature.
4. Metals from unstable hydrides.	4. Non-metals from stable hybrides.
5. Metals from hydroxides in water.	5. Non-metals do not react with water.

Question 6.
List different uses of metals that you come across in everyday life.
Answer:
Uses of Metals :

1. Iron alloyed with other metals is used in trains, automobiles, aeroplanes, satellites and industrial gadgets.
2. Iron in conjunction with cement is used to construct big buildings.
3. Aluminium and its alloys are used in making house hold items and aeroplanes.
4. Metals like copper, iron and aluminium are used in making cooking utensils and water boilers.
5. Copper and alunimium are used in electric wires.
6. Gold and silver are used in making electrical contacts in computers and solar cells and jewellery.
7. Aluminium foils are used as packing material.
8. In combined form metals are used as salt, cement and glass.