Which of the following can be beaten into thin sheets?
(a) Zinc
(b) Phosphorus
(c) Sulphur
(d) Oxygen
Option (a) is correct.
Zinc is a metal and the rest are non-metals. Due to the property of malleability of metals, metals can be beaten into sheets and not non-metals. Thus, Zince can be beaten into sheets.
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.
Option (c) is correct
Generally, metals are ductile because they can be drawn into wires.
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 to acids to produce hydrogen gas.
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) False. Metals also react with acids.
(b) True. Because it is an alkali metal.
(c) False. Because zinc is more reactive than copper.
(d) False. Because Coal is not a metal.
Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these properties.
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.
(a) Aluminium foils are used to wrap food items because aluminium metal is malleable. Therefore, it can be beaten into thin sheets called foils.
(b) Metals are good conductors of heat and electricity. Therefore, immersion rods for heating liquids are made of metallic substances, so that they can conduct heat and electricity.
(c) A metal can displace a less reactive metal from its salt in an aqueous solution. Because zinc is more reactive than copper. Therefore, copper cannot displace zinc from its salt solution (as shown in equation 1). But, Zinc can displace copper form its salt solution.
Cu(s)+ ZnSO4(aq)→No reaction …………… (1)
Zn(s)+ CuSO4(aq)→ZnSO4 ……………… (2)
(d) Sodium and potassium are stored in kerosene because they are highly reactive elements. They can easily catch fire even when in contact with air.
Can you store lemon pickle in an aluminium utensil? Explain.
Lemon pickle cannot be stored in aluminium utensils because lemon pickle contains acids, which can react with aluminium. Because aluminium is a metal and metals react with acids to liberate hydrogen gas. This can lead to the spoiling of the pickle.
Match the substances given in Column A with their uses given in Column B.
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.
(a) When dilute sulphuric acid is poured on a copper plate, bubbles of hydrogen gas appear on the surface of plate.
This happens because The copper being a reducing agent reacts with sulphuric acid to produce hydrogen gas. This can be shown by following equation:
This can be shown by the following equation:
H2SO4 (l) + Cu (m) → CuSO4 (l) + H2 (g)↑
sulphuric acid Copper Copper sulphate Hydrogen gas
(b)When we add iron in the copper sulphate solution. The blue colour of copper sulphate fades and there is deposition of copper on the iron nail.
Iron being more reactive displaces copper from copper sulphate solution.
This can be shown by the following equation:
Fe(s) + CuSO4 (l) → FeSO4(l) + Cu(m)
Iron Copper sulphate Ferrous sulphate Copper
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.
After Saloni has collected the gas evolved in the test tube.
(a) Add a few drops of water in the test tube containing gas. Now, cover the test tube and shake it well. After shaking, test the solution with blue litmus and red litmus. It will turn blue litmus red. Thus, the gas is acidic in nature. If it would not have changed the colour of litmus that means gas was basic.
(b) Charcoal reacts with oxygen to form carbon dioxide gas.
C (Carbon from Charcoal) + O2 (Oxygen) → CO2 (Carbon Dioxide)
Carbon dioxide reacts with water to form carbonic acid, which turns blue litmus paper red.
CO2 (Carbon Dioxide) + H2O (Water) → H2CO3 (Carbonic Acid)
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?
To polish a gold ornament, it is dipped in a liquid called aqua regia (a mixture of hydrochloricacid and nitric acid in ratio 3:1).
The gold layer starts dissolving when put in aqua regia which causes reduction in the weight of gold amount. The outer layer of gold dissolves and the inner shiny layer appears.