NCERT Solutions for Class 8th Science

Chapter 4 – MATERIALS: METALS AND NON-METALS

(Complete Downloadable Chapter Solution PDF file is at the bottom of the page)

 

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:

           (a) Phosphorus is very _________ non-metal.

           (b) Metals are _________ conductors of heat and __________.

           (c) Iron is _________ reactive than copper.

           (d) Metals react with acids to produce ________ gas.

Ans    (a) Phosphorus is 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.

Q.4      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. ( )

Ans     (a) Generally, non-metals react with acids. (F)

           Correct: Generally, metals react with acids.

Q.5      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

Q.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 are used to wrap food items because aluminium metal is highly malleable and can be            beaten into thin sheets. Moreover, it does not react with food items and alter their taste.

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

Q.8      In the following Table some substances are given in Column I. In Column II some uses are given. Match the items in column I with those in Column II.

Column I                                     Column II

(i) Gold                                    (a) Thermometers

(ii) Iron                                    (b) Electric wire

(iii) Aluminium                        (c) Wrapping food

(iv) Carbon                              (d) Jewellery

(v) Copper                               (e) Machinary

(vi) Mercury                            (f) Fuel

Q.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.

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.

Q.11    One day Reeta went to a jeweller’s shop with her mother. Her mother gave 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?