NCERT Solutions for Class 8 Science Chapter 4 Materials Metals and Non Metals

Metals and Non-Metals Class 8 Science NCERT Textbook Questions & Answer

Q 1- Which of the following can be beaten into thin sheets?

            (A) Zinc                              (B) Phosphorus                   (C) Sulphur                          (D) Oxygen

Ans.       (A) Zinc

Q 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.    (C) Generally, metals are ductile.

Q 3- Fill in the blanks.

            (i)  Phosphorus is a very …………… non-metal.

            (ii) Metals are  …………… conductors of heat and  ……………

            (iii) Iron is  …………… reactive than copper.

            (iv) Metals react with acids to produce …………… gas.

Ans.       (i) Reactive    (ii) Good, electricity    (iii) More    (iv) Hydrogen

Q 4- Mark ‘T’ if the statement is true and ‘F’ if it is false.

            (i)  Generally, non-metals react with acids.

            (ii) Sodium is a very reactive metals.

            (iii) Copper displaces zinc from zinc sulphate solution

            (iv) Coal can be drawn into wires.

Ans.    (i) F    (ii) T    (iii) F    (iv) F

Q 5- Some properties are listed in the following table. Distinguish between metals and non-metals on the basis of these properties.

Ans-

Q  6- Give reasons for the following :

            (i)  Aluminium foils are used to wrap food items

            (ii) Immersion rods for heating liquids are made up of metallic substances.

            (iii) Copper cannot displace zinc from its salt solution

            (iv) Sodium and potassium are stored in kerosene.

Ans.    (i)  Aluminium is highly malleable metal and it is very easy to make aluminium foil in compare to other metals.

            (ii) Immersion rods are made up of metallic substances because metals are good conductors of heat and electricity.

            (iii) Copper cannot displace zinc from its solution because zinc is more reactive than copper (i.e., copper is less reactive than zinc.)

               (iv) Sodium and potassium metals are very reactive because they react with oxygen and water easily. A lot of heat is produced in the reaction so sodium and potassium are always stored and kerosene.

Q 7- Can you store lemon pickle in an aluminum utensil? Explain.

Ans.    No. this is because acids react with aluminum.

Q 8-Match the substances given in Column-A with their uses given in Column-B.

Ans-

Q 9- What happens when

            (i)  Dilute sulphuric acid is poured on a copper plate?

            (ii) Iron nails are placed in copper sulphate solution?

            Write word equations of the reactions involved.

Ans.    (i)  Copper sulphate is formed and hydrogen gas is liberated.

                  Copper + Sulphuric acid ———> Copper sulphate + Hydrogen (gas)

            (ii) Brown coating is deposited on the iron nails. This is because of the displacement of copper from copper sulphate solution by iron.

                  Iron + Copper Sulphate (solution)———–> Iron sulphate (solution) + Copper

Q 10- Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.

            (i)  How will she find the nature of the gas?

            (ii) Write down word equations of all the reactions taking place in this process.

Ans.    (i)  She will bring a wet litmus paper in contact with the gas. If the gas turns wet blue litmus paper into red, the gas will be acidic.

            (ii) (a) Carbon + Oxygen  ———-> Carbon dioxide.

                  (b) Carbon dioxide + Water ————-> Carbonic acid. (from wet litmus)

Q 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 slight loss in its weight. Can you suggest a reason for the loss in weight?

Ans.       The jeweller dip the jewellery in the solution of acid, which reacts with the outer covering of metals. Thus there is a net loss of weight in the metal of the ornament.