\nvi. Mercury<\/td>\n | f. Fuel<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Answer: \n(i) \u2192 d, \n(ii) \u2192 e, \n(iii) \u2192 c, \n(iv) \u2192 f, \n(v) \u2192 b, \n(vi) \u2192 a<\/p>\n <\/p>\n Question 9. \nWhat happens when \na. Dilute sulphuric acid is poured on a copper plate? \nb. Iron nails are placed in copper sulphate solution? \nWrite word equations of the reactions involved. \nAnswer: \na. Copper does not react with dilute sulphuric acid. So, no reaction takes place when dilute sulphuric acid is poured on a copper plate. However, when concentrated sulphuric acid is poured on copper plate, hydrogen gas evolves along with the formation of blue coloured copper sulphate crystals. \nCu + H2<\/sub>SO4<\/sub> (conc.) \u2192 CuSO4<\/sub> + H2<\/sub>O \nCopper + Dilute sulphuric acid \u2192 No reaction<\/p>\nb. When iron nails are placed in copper sulphate solution, the blue colour of copper sulphate solution is replaced by a light green colour. This happens because, iron being more reactive than copper, displaces copper from copper sulphate and makes iron sulphate solution. \nCopper sulphate (blue) + Iron \u2192 Iron sulphate (light green) + Copper \nFe + CuSO4<\/sub> \u2192 FeSO4<\/sub> + Cu<\/p>\nQuestion 10. \nSaloni took a piece of burning charcoal and collected the gas evolved in a test tube. \na. How will she find the nature of the gas? \nb. Write down word equations of all the reactions taking place in this process. \nAnswer: \na. Saloni should bring a wet blue litmus paper near the evolved gas. If litmus paper turns to red, it indicates that the evolved gas is acidic in nature.<\/p>\n b. Carbon (in charcoal) reacts with oxygen to produce carbon dioxide gas. \nC + O2<\/sub> \u2192 CO2<\/sub> \nCarbon dioxide reacts with water to form carbonic acid. \nCO2<\/sub> + H2<\/sub>O \u2192 H2<\/sub>CO3<\/sub> (acidic)<\/p>\nQuestion 11. \nOne day Reeta went to a jeweller\u2019s 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? \nAnswer: \nJewellers use aqua regia to clean the jewellery. Gold is an inert metal which does not react with acids. But aqua regia is a mixture of hydrochloric acid and nitric acid in 3 : 1 ratio. It is so potent that it even dissolves gold and silver. Some of the gold is thus lost during the cleaning of jewellery. This explains the weight loss in jewellery.<\/p>\n NCERT Extended Learning Activities and Projects<\/span><\/p>\nQuestion 1. \nPrepare Index Cards for any four metals and four non-metals. The card should have information like name of metal\/non-metal; its physical properties, chemical properties and its uses. \nHint: \nUses of Metals<\/p>\n |