NCERT Solutions Class 8 Science Chapter 4 Materials : Metals And Non-Metals
NCERT Solutions Class 8 Science Chapter 4 Materials : Metals And Non-Metals: National Council of Educational Research and Training Class 8 Science Chapter 4 Solutions – Materials : Metals And Non-Metals. NCERT Solutions Class 8 Science Chapter 4 PDF Download.
NCERT Solutions Class 8 Science Chapter 4: Overview
|Materials : Metals And Non-Metals|
NCERT Solutions Class 8 Science Chapter 4 – Materials : Metals And Non-Metals
CHAPTER: – 4
(MATERIALS: METALS AND NON-METALS)
1)Which of the following can be beaten into thin sheets?
(a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen.
Ans: – Option(a) Zinc.
Explanation –(Because of ductility)
2) 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.
Ans: – Option(c).
Explanation – Gold is the most ductile metal.
3) Fill in the blanks.
(a) Phosphorus is a very __reactive_____non-metal.
Explanation – (As there are free electron in last shell)
(b) Metals are ___good____conductors of heat and___electricity__.
Explanation -(There present free electron in metal)
(c) Iron is __more____reactive than copper.
Explanation – (Iron last electron easily participate in reaction rather than copper)
(d) Metals react with acids to produce___hydrogen _____ gas.
Explanation – (The nature of metal is while reacting with hydrogen produce its oxide and hydrogen)
4) Mark ‘T’ if the statement is true and ‘F’ if it is false.
(a) Generally, non-metals react with acids.
Ans: – False.
Explanation – (Metal react with acids generally)
(b) Sodium is a very reactive metal.
Ans: – True.
Explanation – (For this reason, it stores in kerosene)
(c) Copper displaces zinc from zinc sulphate solution.
Ans: – False.
Explanation -(Copper is more reactive)
(d) Coal can be drawn into wires.
Ans: – False.
Explanation – (For this metal is needed)
5)Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties.
|1.Apearance||Metallic lustre is present.||There is absent in lustre.|
|2.Hardness||Comparatively hardness except sodium.||Generally soft in nature.|
|3.Mallebility||Comparatively malleable in nature||Non malleable.|
|4.Ductility||Ductile in nature.||Ductility doesn’t see|
|5.Heat conduction||Good conductor of heat.||Bad conductor of heat.|
|6. Electricity conduct||Good conductor of electricity.||Bad conductors of electricity or doesn’t conduct electricity|
6)Give reasons for the following.
(a) Aluminium foils are used to wrap food items.
(b) Immersion rods for heating liquids are made up of metallic substances.
(c) Copper cannot displace zinc from its salt solution.
(d) Sodium and potassium are stored in kerosene.
Ans: – (a) Aluminium foils helps in wrap food items as according to the properties of aluminium it helps in maintain the heat balance throughout time so the food remain in good quality and doesn’t become rancid as air also doesn’t flow through it.
(b)As we know metal is ductile in nature which properties of metal helps in making the rod. And by using this property iron is made to the iron rod by applying pressure on it.
(c)From the properties of the copper and zinc we know that the copper is more reactive than the zinc so it from salt by reaction.
(d)As sodium and potassium is more reactive in a metal series and it from compound by reacting moisture. So, for this reactivity it keeps in kerosene.
7) Can you store lemon pickle in an aluminium utensil? Explain.
Ans:- From the properties of the metal we came to know that metal react with the acids and forms salt and oxide. So, as lemon is acidic in nature it should not be kept in metal like aluminium.
8) Match the substances given in Column A with their uses given in Column B.
|(c) Aluminium.||Wrapping food|
|(e) Copper.||Electric wire|
9)What happens when
(a) Dilute sulphuric acid is poured on a copper plate?
(b) Iron nails are placed in copper sulphate solution? Write word equations of the reactions involved.
Ans: – (a) dill.H2SO4 + Cu—> CuSO4 + H2.
Dilute sulphuric acids react with copper when it kept in copper plate and produce copper sulphate and hydrogen gas.
(b) Fe + CuSO4 (FeSO4 + Cu;)
Iron nails when places in copper solution after reaction it produces ferrous sulphate and copper remaining in the places.
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.
Ans: – For this identity we there should be a litmus in of wet in nature which after placing closed to it this colour will be changed from blue to red.
C + O2 —-> CO2;
CO2 + H2O —> H2CO3.
11) One day Reeta went to a jeweller’s 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?
Ans: – The jewellers clear the shop with the acidic solution. So, when Reeta went to a jewellers shop for cleaning for this gold react with the acidic solution. After this reaction some amount of weight is lost. So, after that when Reeta brought back the jewellery that become slightly less amount.