Please give me extra questions of kshitij class tenth of ch- 1
1. On what chemical law, balancing of chemical equation is based? 2. Identify the compound oxidized in the following reaction: S (s) + HCl (g)®H2S (g) + Cl2 (g) 3. Give an example of photochemical reaction. 4. Name the reaction which forms insoluble salts. 5. Name the product obtained and type of reaction given below: _________ + ________®Na2SO4 + BaCl2 6. Explain the following in terms of gain or loss of oxygen with one example: a. Oxidation b. Reduction 7. A copper coin is kept in a solution of silver nitrate for some time, what will happen to the coin and the colour of the solution? 8. Why do we apply paint on iron articles? 9. What happens chemically when quicklime is added to water? 10. What is rancidity? Write the common methods to prevent it. 11. What is corrosion? State the conditions necessary for rusting of iron. How rusting is harmful? 12. Name the type of reactions in the following cases: a. Garbage producing foul smell b. Burning of natural gas. c. Carbon dioxide gas passed through lime water. 13 13. Blue crystals of copper sulphate on heating in a dry test tube become colourless. Give reasons. 14. a. Why can not a chemical change be normally reversed? b. Why is it always essential to balance a chemical equation? c. What happens when CO2 gas is passed through lime water and why does it disappear on passing excess CO2? d. Can rusting of iron take place in distilled water? HOTS QUESTIONS (SOLVED) Q.1. A water insoluble substance ‗X‘ on reacting with dilute H2SO4 released a colourless and odourless gas accompanied by brisk effervescence. When the gas was passed through water, the solution obtained turned blue litmus red. On bubbling the gas through lime water, it initially became milky and milkyness disappeared when the gas was passed in excess. Identify the substance ‗X‘. Write its chemical equations of the reactions involved. Ans. The water insoluble substance ‗X‘ is metal carbonate CaCO3. CaSO4(Aq) + H2O (Aq) + CO2 (G)®CaCO3 (S) + H2SO4 (Aq) CaCO3 (S) + H2O (L)®Ca(OH)2 + CO2 (G) (milky) CaHCO3®CaCO3 (S) + CO2 (G)+ H2O (Aq) (milkiness disappeared) Q.2. Ahmad took a magnesium ribbon (cleaned) and burned it on a flame. The white powder formed was taken in a test tube and water was added to it. He then tested the solution formed with red and blue litmus paper. What change was seen? Why? Ans. Red litmus paper turned blue. Blue litmus paper remained blue. This is because the magnesium ribbon on burning in air forms the white magnesium oxide. Which dissolved in water, it forms magnesium hydroxide, which is Basic in nature. Q.3. Give one example of a combination reaction in which an element combines with a compound to give you a new compound. 2SO3®Ans. O2 + 2SO2 6NH4Cl +N2®8NH3 + 3Cl2 Q.4. Marble statues often slowly get corroded when kept in open for a long time. Assign a suitable explanation. Q.5. Mohan took pure water for the electrolytic decomposition of water but did not see any bubbles near the electrodes. Explain why? Q. 6 Rancidity is a process used for spoiling of cooked food materials like vegetables, etc. When kept for long time in open. How can you prevent such process to proceed? Give an example. Q. 7 A substance ‗X‘ displaces ‗Y‘ from its solution in water. It is called displacement reaction. 14 What other chemical name can be given to such type of reactions? Explain, giving an example? Q. 8 A grey coloured metal ‗Z‘ (Atomic weight=65) is used in making dry cell. It reacts with dil. HCl to liberate a gas. What is the gas evolved? Calculate the minimum amount of ‗Z‘ required to produce 100 litre of gas? Q. 9 Why respiration is considered an exothermic reaction? Explain. Q. 10 Why photosynthesis is considered an endothermic reaction? Explain. Q. 11 Why decomposition reactions are called opposite of combination reactions? Write equations for these reactions. Q. 12 A shiny brown coloured element ‗X‘ on heating in air becomes a black coloured compound. Name the element ‗X‘& black the coloured compound formed. Also write the equation
