is a liquid at room temperature.
Answer: Mercurycan be easily cut with a knife.
Answer: Sodiumis the best conductor of heat.
Answer: Silveris a poor conductor of heat.
Answer: Lead
Explain the meanings of malleable and ductile.
Answer: Malleable: Metals can be beaten into thin sheets and hence they are called malleable.Ductile: Metals can be drawn into thin wires and hence they are called ductile.A malleable metal is also ductile and these properties are present in almost all the metals.Why is sodium kept immersed in kerosene oil?
Answer: Sodium is a highly reactive metal and it reacts vigorously with water even at room temperature. Sodium is so reactive that it can even react with the atmospheric moisture. This reaction is highly exothermic which produces fire as well. Sodium is kept immersed in kerosene oil to prevent its reaction with water and to prevent accidental fire.Write equations for the reactions of iron with steam
Answer:3Fe + 4H2O ⇨ Fe3O4 + 4H2calcium and potassium with water
Answer:Ca + 2H2O ⇨ Ca(OH)2 + H22K + 2H2O ⇨ 2K(OH)2 + H2
| Metal | Iron(II) sulphate | Copper(II) sulphate | Zinc sulphate | Silver nitrate |
|---|---|---|---|---|
| A | No reaction | displacement | ||
| B | Displacement | No reaction | ||
| C | No reaction | No reaction | No reaction | Displacement |
| D | No reaction | No reaction | No reaction | No reaction |
Which is the most reactive metal?
Answer: B is the most reactive metalWhat would you observe if B is added to a solution of Copper(II) sulphate?
Answer: When B is added to copper (II) sulphate solution, it displaces copper.Arrange the metals A, B, C and D in the order of decreasing reactivity.
Answer: B > A > C > DWhich gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H2SO4 Answer: When a reactive metal reacts with dilute hydrochloric acid, hydrogen gas is produced. The chemical equation for reaction between iron and dilute hydrochloric acid is as follows:Fe + H2SO4 ⇨ FeSO4 + H2
What would you observe when zinc is added to a solution of iron(II) sulphate? Write the chemical reaction that takes place.
Answer: Zinc displaces iron from iron (II) sulphate solution because zinc is more reactive than iron. This reaction can be shown by following equation:Zn + FeSO4 ⇨ ZnSO4 + FeAnswer the following questions: Write the electron-dot structures for sodium, oxygen and magnesium.
Answer: Electronic dot structure of Na(11)Electronic dot structure of O (8):Electronic dot structure of Mg (12):Show the formation of Na2O and MgO by the transfer of electrons.
Answer: Electron dot structures of sodium oxide and magnesium oxide are as follows:What are the ions present in these compounds?
Answer: In both the compounds; oxide ions are present. Sodium ion is present in sodium oxide, while magnesium ion is present in magnesium oxide.
Why do ionic compounds have high melting points?
Answer: The force of attraction in ionic bonds is very strong and it is difficult to overcome that force. Hence, ionic compounds have high melting points.Define the following terms. Mineral
Answer: A substance which naturally occurs in the earth’s crust and has a uniform composition is called mineral.Ore
Answer: A mineral from which a substance can be profitably extracted is called an ore.Gangue
Answer: The impurities present in an ore are called gangue.
Name two metals which are found in nature in the free-state.
Answer: Silver and goldWhat chemical process is used for obtaining a metal from its oxide?
Answer: For obtaining a metal from its oxide, we need to use reduction. This process is carried out by heating the metal oxides; usually with a reducing agent.Metallic oxides of zinc, magnesium and copper were heated one by one with zinc, magnesium and copper. In which cases will you find displacement reactions taking place?
Answer: Displacement reaction takes place only when zinc oxide is headed with magnesium. And No reaction takes place in other cases.Which metals do not corrode easily?
Answer: Metals which are at the bottom of reactivity series do not corrode easily, e.g. copper, silver and gold.What are alloys?
Answer: A homogenous mixture of two or more than two metals or a metal and a non-metal is called an alloy.Which of the following pairs will give displacement reactions? NaCl solution and copper metal MgCl2 solution and aluminium metal FeSO4 solution and silver metal AgNO3 solution and copper metal.
Answer: (d) AgNO3 solution and copper metal.
Which of the following methods is suitable for preventing an iron frying pan from rusting? Applying grease Applying paint Applying a coating of zinc All of the above.
Answer: (c) Applying a coating of zinc
An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be Calcium Carbon Silicon Iron
Answer: (a) Calcium
Food cans are coated with tin and not with zinc because zinc is costlier than tin. zinc has a higher melting point than tin. zinc is more reactive than tin. zinc is less reactive than tin.
Answer: (c) zinc is more reactive than tin.
You are given a hammer, a battery, a bulb, wires and a switch. How could you use them to distinguish between samples of metals and non-metals?
Answer: If a substance can be beaten into thin sheets with the help of a hammer then the given substance is a metal. Otherwise, it is a non-metal. A circuit is made with the help of a battery, a bulb, wires and a switch. After that, the given substance is connected in the circuit. If the given substance ensures that the circuit is complete then it is a metal; else it is a non-metal.Assess the usefulness of these tests in distinguishing between metals and non-metals.
Answer: When a substance fulfills both the criteria then it can be confirmed as a metal. We know that some of the metals are brittle and graphite (a non-metal) is a good conductor of electricity. Hence, either of the tests cannot confirm a metal or non-metal; when the test is done in isolation.
What are amphoteric oxides? Give two examples of amphoteric oxides.
Answer: Some oxides show both acidic and basic characters. Such oxides are called amphoteric oxides. Amphoteric oxide reacts with acid as well as with base to form salt.Example: Aluminium oxide and zinc oxide are examples of amphoteric oxide. When aluminium oxide reacts with a base, it gives salt and water.Al2O3 + 2NaOH ⇨ 2NaAlO2 + H2OWhen aluminium oxide reacts with an acid it gives salt and water.Al2O3 + 6HCl ⇨ 2AlCl3 + 3H2OPratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it. What will be the action of gas on dry litmus paper?
Answer: There will be no action on dry litmus paper.moist litmus paper?
Answer: Since the gas is an oxide of a non-metal hence it will turn moist blue litmus paper to red.
Write a balanced chemical equation for the reaction taking place.
Answer: S + O2 ⇨ SO2
Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Answer: Sodium and zinc can displace hydrogen from dilute acids. On the other hand, copper and silver do not displace hydrogen from dilute acids.In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Answer: A rod of impure metal M would be used as anode and a thin strip of pure metal M would be used as cathode. A water soluble salt of metal M would be used as electrolyte.State two ways to prevent the rusting of iron.
Answer: Two ways to prevent the rusting of iron are as follows:- By galvanization
- By applying a layer of paint
What type of oxides are formed when non-metals combine with oxygen?
Answer: The non-metallic oxides are acidic in nature.Platinum, gold and silver are used to make jewellery. Why?
Answer: Platinum, gold and silver are at the bottom of the reactivity series and hence they are able to maintain their shine for a long time. Moreover, these are highly ductile and malleable. Hence, these metals are used to make jewelry.
Sodium, potassium and lithium are stored under oil. Why?
Answer: Sodium, potassium and lithium are at the top of the reactivity series. They can easily react with water and even with atmospheric moisture. Their reaction with water is highly exothermic and results in fire. These metals are stored under oil to prevent their reaction from water and to prevent accidental fire.
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