Metals with oxygen and acids

This type of question, asked 4 times: 2023, 2024, 2025, 2026. All 8 questions below, oldest first.

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Question 1 (case study, 4 parts)
2023
Almost all metals combine with oxygen to form metal oxides. Metal oxides are generally basic in nature. But some metal oxides show both basic as well as acidic behaviour. Different metals show different reactivities towards oxygen. Some react vigorously while some do not react at all.
37 (a) $What happens when copper is heated in air ? (Give the equation of the reaction involved).$
37 (b) $Why are some metal oxides categorized as amphoteric ? Give one example.$
37 (c) $\mathrm{Na_2O_{(s)} + H_2O_{(l)} \rightarrow}$
37 (c) OR $On burning Sulphur in oxygen a colourless gas is produced. (i) Write chemical equation for the reaction. (ii) Name the gas formed. (iii) State the nature of the gas. (iv) What will be the action of this on a dry litmus paper ?$
Question 2
2024
28 $Suggest an activity to differentiate between the chemical properties (acidic or basic character) of the product obtained on burning a metal (magnesium) and a non-metal (sulphur).$
Question 3 (case study, 4 parts)
2024
Three metal samples of magnesium, aluminium and iron were taken and rubbed with sand paper. These samples were then put separately in test tubes containing dilute hydrochloric acid. Thermometers were also suspended in each test tube so that their bulbs dipped in the acid. The rate of formation of bubbles was observed. The above activity was repeated with dilute nitric acid and the observations were recorded.
37 (a) $When activity was done with dilute hydrochloric acid, then in which one of the test tubes was the rate of formation of bubbles the fastest and the thermometer showed the highest temperature ?$
37 (b) $Which metal did not react with dilute hydrochloric acid ? Give reason.$
37 (c) (i) $Why is hydrogen gas not evolved when a metal reacts with dilute nitric acid ? Name the ultimate products formed in the reaction.$
37 (c) (ii) $Name the type of reaction on the basis of which reactivity of metals is decided. You have two metals X and Y. How would you decide which is more reactive than the other ?$
Question 4
2024
28 $State reasons for the following : (a) Zinc oxide is an amphoteric oxide. (b) Calcium starts floating when immersed in water. (c) In the reactions of nitric acid with metals, generally hydrogen gas is not evolved.$
Question 5
2024
27 $State reasons for the following : (a) Zinc oxide is an amphoteric oxide. (b) Sodium metal is stored in bottle filled with kerosene oil. (c) In the reactions of nitric acid with metals, generally hydrogen gas is not evolved.$
Question 6
2025
2 $The products formed when Aluminium and Magnesium are burnt in the presence of air respectively are :$
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Question 7
2025
34 (a) $(i) Consider the following metals : K, Ca, Al, Cu, Ag, Fe Select from the above metals, a metal which I. does not react with oxygen even at high temperature. II. reacts with oxygen at ordinary temperature and forms a protective oxide layer which prevents the metal from further oxidation. III. catches fire when kept in the open. IV. does not burn in oxygen but the hot metal is coated with a black coloured oxide layer. (ii) What are amphoteric oxides ? With the help of balanced chemical equations show that aluminium oxide is an amphoteric oxide. (iii) What are alkalis ? Give one example.$
Question 8
2026
19 $Magnesium ribbon burns with a dazzling white flame and changes into a white powder as shown in the diagram given below : The powder is dissolved in water. Identify the chemical formula of the white powder and the correct change observed when the solution is tested with litmus paper.$
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Metals with oxygen and acids

Question 1 (case study, 4 parts)

Question 2

Question 3 (case study, 4 parts)

Question 4

Question 5

Question 6

Question 7

Question 8