Question 1. Which of the following can be beaten into thin sheets?
(a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen
Solution : (a) Zinc
Question 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.
Solution : (c) Generally, metals are ductile.
Question 3. 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.
(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.
Question 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. ( )
(a) Generally, non-metals react with acids. ( F)
(b) Sodium is a very reactive metal. ( T)
(c) Copper displaces zinc from zinc sulphate solution. ( F)
(d) Coal can be drawn into wires. ( F)
Question 5. Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties.
|5. Heat conduction||————||————|
|6. Conduction of Electricity||————||————|
|2. Hardness||Very hard||Hard or Soft|
|3. Malleability||Malleable||Not malleable|
|4. Ductility||Ductile||Non ductile|
|5. Heat conduction||Conductor of heat||Non-conductor of heat|
|6. Conduction of Electricity||Conductor of electricity||Non conductor of electricity|
Question 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.
(i) In an aqueous solution, a metal can displace a less reactive metal from its salt. But zinc is more reactive than copper. And because of it, copper cannot displace zinc from its salt solution.
Cu(s) +ZnSO4 (aq) → No reaction ……………… (1)
Zn(s)+ CuSO4 (aq) → ZnSO4 ……………… (2)
(ii) Aluminium foils are used to wrap foods items because aluminum metal is malleable and it can be beaten into foil.
(iii) Sodium and potassium are stored in kerosene because they are highly reactive elements and can easily catch fire with the contact of air.
(iv) Immersion rods for heating liquids are made up of metallic substances because metals are good conductors of heat and electricity.
Question 7. Do you think it is possible to store lemon pickle in an aluminum utensil?
Solution : No, it is not possible to store lemon pickle in an aluminum utensil because lemon pickle contains an acid which can react with aluminum (metal) liberating hydrogen gas. This may spoil the pickle.
Question 8. Match the following with column A with column B
a) Iron i) Wrapping food
b) Mercury ii) Jewellery
c) Carbonn iii) Fuel
d) Gold iv) Thermometer
e)Copper v) Machinery
f) Aluminum vi) Electric Wires
a) Iron v) Machinery
b) Mercury iv) Thermometer
c) Carbon iii) Fuel
d) Gold ii) Jewellery
e)Copper vi) Electric Wires
f) Aluminum i) Wrapping food
Question 9. What happen when:
(i) Iron nails are placed in copper sulphate solution?
(ii) Dilute sulphuric acid is poured on a copper plate?
Write word equations of the reaction involved
(a) When dilute sulphuric acid is poured on a copper plate, copper reacts with sulphuric acid to release hydrogen gas.
Cu + H2SO4 → CuSO4 + H2
(Copper) (Sulphuric Acid) (Copper Sulphate) (Hydrogen Gas)
(b) When iron nails are placed in copper sulphate solution, iron will displace copper from copper sulphate solution with the blue colour of copper sulphate fading.
Fe + CuSO4 → FeSO4 + Cu
(Iron) (Copper Sulphate) (Iron Sulphate) (Copper)
Question 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.
(a) To find the nature of the gas, add some water in the test tube. Now, shake the test tube well covering it properly. Test the solution with blue and red litmus paper. It will be observed that blue litmus turns red which means the nature of gas is acidic.
(b) When a piece of charcoal is burnt, it reacts with oxygen to release carbon dioxide gas.
C + O2 → CO2
(Charcoal) (Oxygen) (Carbon Dioxide)
Question 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?
Solution : In order to polish the gold ornament, it is to be dipped into a liquid called aqua regia (a mixture of hydrochloric acid and nitric acid). On getting dissolved in the environment of aqua regia, the outer layer of gold dissolves and an inner shiny layer appears. The dissolving of the layer causes a reduction in the weight of the jewelry.