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Q1 Which of the following can be beaten into thin sheets? (a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen Ans: (a) Zinc
The properties of metal by which they can be beaten into thin sheets is called malleability. For example: zinc.
Q2 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
Generally metals are ductile but some exceptions are there like mercury is a metal which is liquid at room temperature. It cannot be drawn into wires, so it is not ductile.
Q3 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) Reactive
Phosphorus is an reactive non- metal. It catches fire easily when exposed to air.
(b) Good, electricity
Conductors are those from which heat and electricity can pass through easily. Metals are good conductor of heat and electricity.
(c) More
Iron is more reactive than copper so it can replace copper easily from its solution.
(d) Hydrogen
When metal reacts with acid. It produces hydrogen gas which burns with a pop sound whereas non- metal generally do not react with acids.
Q4 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) False
This statement is false because non- metals generally do not react with metal whereas metal does.
(b) True
This statement is true because, sodium is a very reactive metal. It is stored in kerosene, it catches fire easily.
(c) False
This statement is false because copper is less reactive than zinc. So, it cannot displace it.
(d) False
This statement is false because coal cannot be drawn into wires. Coal is a form of carbon which is a non- metal. Non- metal does not show the property of ductility.
Q5 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 Ans: - Metals are bright or lustrous in appearance whereas non- metals are dull.
- Generally metals are hard and non- metals are soft.
- Property of metal by which they can be beaten into thin sheets which is known as malleability whereas non- metals does not show this property.
- Property of metals by which they can be drawn into wires are called as ductility whereas non- metal does not show this property.
- Conductors are those from which heat and electricity can pass through easily. Metals are good conductor of heat whereas non- metals are poor conductor of heat.
- Metals are good conductor of electricity whereas non- metals are poor or bad conductor of electricity.
Q6 Give reasons for the following: (a) Aluminium foils are used to wrap food items. (b) Immersion rods 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: - Aluminium is highly malleable and it can easily beaten in the sheets to make its foil for the wrapping purposes. It is also soft and does not reacts with food items; and this is the reason that aluminium foils are used to wrap food items.
- Immersion rods made up of metallic substances because metals are good conductor of heat and electricity. They get hot very soon on the passage of electric current and warm the water soon.
- Copper is less reactive than zinc. So, it cannot displace zinc from its solution.
- Sodium and potassium are highly reactive, so they are stored in kerosene.
Q7 Can you store lemon pickle in an aluminium utensil? Explain. Ans: No, we cannot store lemon pickle in an aluminium utensil because aluminium is a metal and metals readily react with acid to produce hydrogen. When aluminium comes in contact with lemon, which is acidic, would react to give hydrogen and the pickle will be spoiled.
Q8 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 (ii) Iron (iii) Aluminium (iv) Carbon (v) Copper (vi) Mercury (a) Thermometers (b) Electric Wire (c) Wrapping food (d) Jewellery (e) Machinary (d) Fuel Ans: Column I Column II (i) Gold
(ii) Iron
(iii) Aluminium
(iv) Carbon
(v) Copper
(vi) Mercury(d) Jewellery
(e) Machinary
(c) Wrapping food
(d) Fuel
(b) Electric Wire
(a) Thermometers- Gold is used in making jewelry and making ornaments.
- Iron is a hard metal, it is used in machinery.
- Aluminium is used in wrapping food items, it protect the food items from the bacteria and the humidity.
- Carbon is used as a fuel, in the form of coal and petroleum.
- Copper is a metal which is used in making electric wire because copper is a good conductor of heat and electricity.
- Mercury is a metal which is liquid at room temperature. It is used in thermometers usually.
Q9 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: - No reaction will take place because copper is very less reactive.
- Iron is more reactive than copper and then it will replace copper from its solution and brown coating of copper is deposited on the iron nails. Also, the blue colour turns into the green colour.
Iron + Copper Sulphate (Solution) → Iron sulphate (FeSO4) solution + Copper
Q10 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: - Saloni find the nature of the gas by using a wet litmus paper. After bringing the litmus paper in contact with the gas; if it turns the blue litmus paper into red then it is acidic. Similarly, if it turns the red litmus into blue then it is basic.
- (i) Carbon (C) + Oxygen (O2) → Carbon dioxide (CO2)
(ii) CO2 + Lime water → Milky
Q11 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? Ans: Jeweller dipped the jewelry in a liquid solution called aqua regia to polish a gold ornament. Aqua regia is a mixture of hydrochloric acid and nitric acid. The outer layer of gold is dissolved in aqua regia and the inner shiny layer appears. Reduction of weight of gold is occurs due to the dissolution of outer layer of gold in aqua regia solution.