CLASS VIII SCIENCE Metals and Non-Metals-MCQ & SA

Metals and Non-Metals

Q1. Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen

Answer: (a) Zinc, as it is a metal. Rest of these are non metals.

Q2. Which of the following statements is correct?
(a) All metals are ductile.
(b) All non-metals are ductile.
(c) Generally, metals are ductile.
(d) Some non-metals are ductile.

Answer: (c) Generally, metals are ductile.
Mercury (metal) is liquid at room temperature and cannot be drawn into wires. Therefore, it is non-ductile.




Q3. Fill in the blanks:
(a) Phosphorus is a very _________ non-metal.
(b) Metals are ________ conductors of heat and _________.
(c) Iron is ________ reactive than copper.
(d) Metals react with acids to produce _________ gas.

Answers:
(a) Phosphorus is a very __reactive__ non-metal.
(b) Metals are __good__ conductors of heat and __electricity__.
(c) Iron is __more__ reactive than copper.
(d) Metals react with acids to produce __hydrogen__ gas.

Q4. Mark ‘T’ if the statement is true and ‘F’ if it is false.
(a) Generally, non-metals react with acids. ( )
(b) Sodium is a very reactive metal. ( )
(c) Copper displaces zinc from zinc sulphate solution. ( )
(d) Coal can be drawn into wires. ( )

Answers:
(i) Generally, non-metals react with acids. (F) Generally, metals react with acids.
(ii) Sodium is a very reactive metal. (T)
(iii) Copper displaces zinc from zinc sulphate solution. (F) The reactivity of zinc is higher than copper. So, copper cannot displace zinc from zinc sulphate solution.
(iv) Coal can be drawn into wires. (F) Coal, being a non metal, is non ductile.

Q5. Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties. 

Properties	Metals	Non-Metals
1. Appearance
2. Hardness
3. Malleability
4. Ductility
5. Heat Conduction
6. Conduction of Electricity

Answer:

Properties	Metals	Non-Metals
1. Appearance	They are lustrous.	They are dull
2. Hardness	They are hard.	They are soft.
3. Malleability	They are malleable. Can be beaten into thin sheets	They are not malleable. Cannot be beaten into thin sheets
4. Ductility	They are ductile. Can be drawn into wires	They are not ductile. Cannot be drawn into wires.
5. Heat Conduction	They are good conductors of heat.	They are poor conductors of heat.
6. Conduction of Electricity	Good conductors of electricity	Poor conductors of electricity.

Q6. Give reasons for the following.
(a) Aluminium foils are used to wrap food items. 
Answer: Aluminium foils are used to wrap food items because aluminium is highly malleable. It can be beaten into thin sheets. Moreover, it does not react with food.

(b) Immersion rods for heating liquids are made up of metallic substances.
Answer: Metals are good conductors of heat and electricity. Therefore, immersion rods for heating liquids are made of metallic substances.

(c) Copper cannot displace zinc from its salt solution. 
Answer: The reactivity of zinc is higher than copper. Only a metal of higher reactivity can displace a metal of lower reactivity from its salt solution. So, copper cannot displace zinc from zinc sulphate solution.

(d) Sodium and potassium are stored in kerosene. 
Answer:  Sodium and potassium are highly reactive elements. They can easily catch fire even when they come in contact with air. So, they have to be kept in kerosene.

Q7. Can you store lemon pickle in an aluminum utensil? Explain.
Answer: No, we cannot store lemon pickle in aluminum utensils, as metals react with acids to liberate hydrogen gas. The pickle can be spoiled.

Q8. Match the substances given in Column A with their uses given in Column B.

A	B
(i) Gold	(a) Thermometers
(ii) Iron	(b) Electric wire
(iii) Aluminium	(c) Wrapping food
(iv) Carbon	(d) Jewellery
(v) Copper	(e) Machinery
(vi) Mercury	(f) Fuel

Answer:

A	B
(i) Gold	(d) Jewellery
(ii) Iron	(e) Machinery
(iii) Aluminium	(c) Wrapping food
(iv) Carbon	(f) Fuel
(v) Copper	(b) Electric wire
(vi) Mercury	(a) Thermometers

Q9. What happens when
(a) Dilute sulphuric acid is poured on a copper plate?

Answer: (a) When dilute sulphuric acid is poured on copper, it does not react.
When concentrated sulphuric acid is poured on a copper plate, copper reacts with sulphuric acid to liberate hydrogen gas.

Cu               +   H2SO4              →    CuSO4                        +    H2
Copper            Sulphuric acid        copper sulphate        hydrogen

(b) Iron nails are placed in copper sulphate solution? Write word equations of the reactions involved.

Answer: b) The reactivity of iron is more than copper. So, iron will displace copper from copper sulphate solution.  In this reaction, the blue colour of copper sulphate fades.

Fe   +     CuSO4                  →   FeSO4    +  Cu
Iron      copper sulphate      →  Iron Sulphase + Ccopper

Q.10) Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(a) How will she find the nature of the gas?
(b) Write down word equations of all the reactions taking place in this process.

Answer:
(a) Add some water in the test tube in which gas is collected. Now, cover the test tube. Shake it well. Test the solution with blue litmus and red litmus. Blue litmus turns red. Thus, the nature of gas is acidic.

(b) Charcoal when reacts with oxygen forms carbon dioxide gas.
C      +    O2  →    CO2
Carbon dioxide reacts with water to form carbonic acid, which turns blue litmus paper red.
CO2               +              H2O    →    H2CO3
Carbon dioxide   +   water   →    Carbonic acid

Q11. One day Reeta went to a jeweler shop with her mother. Her mother gave an old gold jewellery to the goldsmith to polish. Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a reason for the loss in weight?

Answer: To polish a gold ornament, it is dipped in an acid (called aqua regia). The outer layer of gold dissolves in the acid and the inner shiny layer is visible. Because of loss of upper layer of jewellery, its weight is reduced.

Q12: List the different uses of metals that you find in your surroundings.

Answer: Metals are used in the following:

1.        machinery

2.        cooking utensils

3.        electrical wires and devices (e.g. heater)

4.        automobiles, planes, ships, trains

5.        construction material e.g. sheets, bars etc.

Q13: Define ductility.

Answer: Ductility is the property of metals due to which the metals can be drawn in to wires.

Q14: What is meant by metallurgy?

Answer: Metallurgy is the science of extracting and purifying metals from their ores.

Q15: What are noble metals? 

Answer: Metals which has the least tendency to react and occur in free state are known as noble metals. Gold, Silver and Platinum as known as noble metals.  They have the property to maintain their metallic lusture for long time.
e.g. Gold does not react with air, water and even with acids. It dissolves in aqua regia (a mix ture of nitric acid + hydrochloric acid).

METALS AND NON METALS :

QUESTION AND ANSWERS

Q1: Identify the type of elements which are neither malleable nor ductile.

Answer: Non-metals (eg Carbon, Phosphorous, Sulphur, Nitrogen) are neither malleable nor ductile.


Q2: Name a property which is common to the metals occurring near the bottom of the reactivity series.

Answer: These (Silver, Gold and Platinum) are least reactive metals and are found in free state in the earth's crust.


Q3: Name a metal that is kept under kerosene.

Answer: Sodium.


Q4: What type of reaction is the reaction between copper sulphate solution and zinc plate?

Answer: It is a displacement reaction.
        Zn + Copper Sulphate ---------> Zinc Sulphate + Copper

(Explanation: Zinc is more reactive than copper, Therefore Zn displaces Cu.)



Q5: An oxide of sulphur turns blue litmus red. Is it acidic or basic?

Answer: Acidic




Q6: Classify the following into metals and non-metals: Iodine, Lead, Carbon, Sulphur, Aluminium, Silicon


Answer: Metals: Lead, Aluminium
               Non-metals: Iodine, Carbon, Sulphur, Silicon


Q7: What is meant by reactivity series of metals?

Answer: The reactivity series of metals is an arrangement of metals in vertical column in order of decreasing reactivity.


Q8: Which of the following are (a) acidic (b) basic oxides?
 Phosphorous pentoxide, Sulphur trioxide, Sodium oxide, Magnesium Oxide

Answer: Acidic Oxides: Phosphorous pentoxide, Sulphur trioxide
  Basic Oxides:  Sodium oxide, Magnesium Oxide

(Explanation: Metal oxides are basic in nature. Non-metal oxides are acidic.)



Q9: Mention one main use of each of the following:
 Copper, Aluminium, Phosphorous and Hydrogen.

Answer: Copper: Making electrical wires and utensils.
  Aluminium:Electrical Wires, Utensils, Paints, Foil for packaging
  Phosphorous: Match Sticks, Fertlizers, Rat Poison
  Hydrogen: As a fuel, In oxygen-Hydrogen Flame for welding, Hydrogenation of Vanaspati Ghee



Q10: Write the word equations for the reaction: Reaction of magnesium with boiling water.

Answer:

  Magnesium + Water     --------------> Magnesium Hydroxide + Hydrogen
                        (boiling)

  Magnesium reacts with boiling water and gives Magnesium hydroxide and hydrogen gas.
    

Q11: Mention some physical properties of metals.

Answer: 1. Most of the metals are solids.
  2. Metals have lusture.
  3. Metals are malleable and ductile.
  4. In general metals are hard and have high tensile strength.
  5. Metals have high melting and boiling points.
  6. Metals are good conductor of heat and electricity.
  7. Metals have high density.
  8. Metals are sonorous.


Q12: More reactive metals occur in combined form, whereas less reactive metals occur as free metal in nature. Give reasons.

Answer: More reactive metals react readily with oxygen, carbon-dioxide and water present in air and form oxides, carbonates and hydroxides. That's why reactive metals occur in combined form. Least reactive metals do not react with O2, CO2 or water present in air, thus they are found in free state.


Q13: Describe the reaction:
  Magnesium + Copper Sulphate Solution    --------->    Magensium Suphate + Copper
  in terms of reactivity series of metals.

Answer: According to activity series of metals, Magnesium is more reactive than Copper. Mg displaces Cu and forms Magnesium Sulphate. It is a displacement reaction.


Q14: What is meant by malleability? Name the most malleable metal.

Answer: It is the ability of a metal which can be hammered into thin sheets. Gold and Silver are the most malleable metals.


Q15: Mention the main uses of the following:
     Phosphorous, Sulphur, Copper, Iron, Aluminium, Hydrogen

Answer: Phosphorus: Match Sticks, Fertilizers, Also used in pesticides and water treatment.
  Sulphur: Gun Powder, Sulphuric Acid preparation, Vulcanization of rubber.
  Copper: Electrical wires and cables, utensils, coins
  Iron: Bridges, Engine Parts, Stainless Steel, Iron Bars used in constructions
  Aluminium: Electric Wires, Utensils, Metallic paint, Aeroplane body
  Hydrogen: As a fuel, Oxy flame used in welding, Hydrogenation of Vegetable ghee.


Q16: Tick the ODD-ONE out giving reason:

  (a) Hydrogen, Oxygen, Suphur, Arsenic, Nonmetal
  (b) Dull, Non-conductor, Brittle, Metal, Non-Metal
  (c) Iron,Zinc, Magnesium, Copper, Sodium
  (d) Sulphur, Phosphorous, Graphite, Carbon
  (e) Zinc Oxide, Sodium Oxide, Magnesium Oxide, Calcium Oxide

Answer:
(a) Arsenic (Reason: Arsenic is a metalloid while remaing ones are non-metals)
(b) Metal (Reason: Rest are properties of Non-Metal)
(c) Copper (Reason: Rest are in order from least reactive to most reactive.)
(d) Graphaite: (Reason: Graphite is an allotrope (type of) of Carbon)
(e) Zinc Oxide (reason: Zinc needs strong heating to form Zinc Oxide while others form oxide at room temperature or little heating.)


Q17: Why are metals/alloys used for making bells?

Answer: Metals and Alloys (containing metal in large and non-metal in small quantity) are sonorous i.e. they give ringing sound when struck hard. Therefore metals/alloys are used for making bells.


Q18: Our body needs iron. Certain foods are rich in iron and iron tablets are recommended by doctors. But neither the food nor the tablets are hard like iron. Explain?

Answer: Iron in food supplements and in tablets is in soluble form and hence can be taken in.

 Class 8 - Science - Coal and Petroleum

Q1:What are the advantages of using CNG and LPG as fuels?
Answer: The advantages of using CNG and LPG as fuels are:

1.        They are used as non-polluting fuels to transport vehicles.

2.        CNG is used for power generation and is a cleaner fuel.

3.        LPG can be used directly for burning in homes and factories.

4.        LPG and CNG has virtually no ash particles left after burning.

Q2:Name the petroleum product used for surfacing of roads.
Answer: Bitumen is the petroleum product used for surfacing of roads.



Q3: Describe how coal is formed from dead vegetation. What is this process called?
Answer: About 300 years ago, the earth consisted of dense forests in low lying wet lands. Due to natural processes, like flooding, these forests got buried under the soil. The temperature rose as they sank deeper and deeper and under high pressure these dead plants got slowly converted into coal.

The process of conversion of dead vegetation into coal is called carbonization as it contains mainly carbon. It is also known as fossil fuel since it is formed from the remains of vegetation.

Q4: Fill in the blanks:
Answer:
(a) Fossil fuels are coal, petroleum and natural gas.
(b) Process of separation of different constituents from petroleum is called refining.
(c) Least polluting fuel for vehicle is CNG.


Q5: Indicate whether the following statements are True (T) or False (F):
Answer: 
(a) Fossil fuels can be made in the laboratory. ✗ False
(b) CNG is more polluting fuel than petrol. ✗ False
(c) Coke is almost pure form of carbon. ✓ True
(d) Coal tar is a mixture of various substances. ✓ True
(e) Kerosene is not a fossil fuel. ✗ False


Q6. Explain why fossil fuels are exhaustible natural resources.
Answer: Fossil fuels are formed over a period of millions of years, by the action of heat and pressure on the remains of dead plants and animals. These fossil fuels are exhaustible natural resources because they can be exhausted by human activities. These fuels cannot be recreated in a short period of time.

Q7. Describe characteristics and uses of coke.
Answer: Coke is a tough porous and black substance. It is produced by destructive distillation of coal.

1.        It is an almost pure form of carbon.

2.        It is used as domestic as well as an industrial fuel in stoves and furnaces.

3.        It is used in the manufacture of steel.

4.        It gives little or no smoke.

5.        It is used for extraction of metals.

6.        It can be used to make fuel gases

Q8. Explain the process of formation of petroleum.

Answer: Petroleum was formed from organisms living in the sea. As these organisms died, their bodies settled down at the bottom of the sea and got covered with sand and clay. The absence of air, high pressure and high temperature for over million of years transformed the dead organisms into petroleum and natural gas. The petroleum deposits are usually found mixed with salt water. The petroleum is lighter than salt water, and hence, floats over it.

Q10: What are Inexhaustible Natural Resources? Give examples.

Answer: These resources are present in unlimited quantity in nature and are not likely to be exhausted by human activities. Examples are: sunlight, air.

Q11: Give examples of natural resources.

Answer: air, water, soil and minerals

Q12: What are Exhaustible Natural Resources? Give examples.

Answer: The amount of these resources in nature is limited. They can be exhausted by human activities. Examples of these resources are forests, wildlife, minerals, coal, petroleum, natural gas etc.

Q13: What is the composition of coal?

Answer: Coal is primarily made up of carbon, also hydrogen, oxygen, nitrogen and some traces of sulphur.

Q14: How coal is obtained?

Answer: Coal is obtained through a process called mining. It is of two types.

1.        Surface mining: It is used when coal is found close to the surface or hillsides.

2.        Underground mining: This method is used to extract coal that is deep beneath the surface of the earth.

 Coal is processed in the industry to get useful products coke, coal tar and coal gas.

Q15: Where coke is used?

Answer: Coke is used in the manufacture of steel and in the extraction of many metals.

Q16: Where was the world's first oil well drilled?

Answer: Pennsylvania, USA, in 1859

Q17: What are the disadvantages of Petroleum?

Answer: Disadvantages are:

1.        Burning of petrol releases carbon dioxide into the air, which not only pollutes air but also contributes to global warming.

2.        Oil spills at sea have devastating impact on marine life and its surroundings.

Q18: Where is petroleum found in India?

Answer: In India, petroleum is found in Assam, Gujarat, Bombay high and in river basins of Godavari and Krishna.

Q19: What are the uses of  kerosene?

Answer: It is used as fuel stoves, lamps and for jet aircrafts.