Doubtly
@Doubtly · Joined Feb 2021
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- State two ways to prevent the rusting of iron. Two ways to prevent the rusting of iron are: → Oiling, greasing, or painting: By applying oil, grease, or paint, the surface becomes water p... 1
- In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte? In the electrolytic refining of a metal M: Anode → Impure metal M Cathode → Thin strip of pure metal M Electrolyte → Solution of salt of the... 1
- Name two metals which will displace hydrogen from dilute acids, and two metals which will not. Iron and aluminium will displace hydrogen from dilute acids as they more reactive then hydrogen. Mercury and copper cannot displace hydrogen... 1
- What are amphoteric oxides? Give two examples of amphoteric oxides. Those oxides that behave as both acidic and basic oxides are called amphoteric oxides. Examples: aluminium oxide (Al₂O₃), zinc oxide (ZnO) 1
- (b) Assess the usefulness of these tests in distinguishing between metals and non-metals. The above tests are useful in distinguishing between metals and non-metals as these are based on the physical properties. No chemical reacti... 1
- (a) How could you use them to distinguish between samples of metals and non-metals? With the hammer, we can beat the sample and if it can be beaten into thin sheets (that is, it is malleable), then it is a metal otherwise a... 1
- Food cans are coated with tin and not with zinc because (a) zinc is costlier than tin. Correct option is (c) zinc is more reactive than tin. 2
- An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. Correct option is (a) calcium 2
- Which of the following methods is suitable for preventing an iron frying pan from rusting? (a) Applying grease Correct option is (c) Applying a coating of zinc 2
- Which of the following pairs will give displacement reactions? (a) NaCl solution and copper metal Correct option is (d) AgNO₃solution and copper metal. 2
- What are alloys? answer An alloy is the homogeneous mixture of two or more metals or metals and non metals. For example brass is an alloy of copper and zinc. 1
- Which metals do not corrode easily? Metals which have low reactivity such as silver, gold does not corrode easily. 1
- Metallic oxides of zinc, magnesium and copper were heated with the following metals. Metal Zinc Magnesium Copper Zinc oxide No reaction Displacement No reaction Magnesium oxide No reaction No reaction No reaction Copper oxide... 1
- What chemical process is used for obtaining a metal from its oxide? A metal can be extracted from its oxide by the process of reduction. 2HgO_((s))→2Hg(I)+O_(2(g)) 1
- Name two metals which are found in nature in the free state. The metals at the bottom of the reactivity series are mostly found in free state. For example: gold, silver, and platinum. 1
- Define the following terms. (i) Mineral (ii) Ore (iii) Gangue (i) Mineral: The naturally occurring compounds of elements are known as Mineral. (ii) Ore: Minerals from which metals can be extracted profi... 1
- Why do ionic compounds have high melting points? Ionic compounds have strong electrostatic forces of attraction between the ions. Therefore, it requires a lot of energy to overcome these fo... 1
- (i) Write the electron-dot structures for sodium, oxygen and magnesium. (ii) Show the formation https://lh3.googleusercontent.com/-5mSXW7_RtTI/Ya5Dz_9aT9I/AAAAAAAAC3w/Hkz-fzukgAUfqc4kUOph7SW-qt6W6uTqACNcBGAsYHQ/image.png (i) The represe... 2