Statement-I: The gas liberated on warming a salt with dil H2SO4, turns a piece of paper dipped in lead acetate into black, it is a confirmatory test for sulphide ion.Statement-II: In statement-I the colour of paper turns black because of formation of lead sulphite. In the light of the above statements, choose the most appropriate answer from the options given below:

A black precipitate formed during the test for sulphur by adding dilute acetic acid to the sodiumfusion filtrate with the addition of a few drops of lead acetate is-----------------A. Acetic acetateB. Lead sulphideC. Sodium acetateD. Sodium sulphide

An aqueous solution of a given salt was made alkaline with solid NH4CI and NH4OH solution. H2S gas was then passed through the test tube. A black ppt. appeared. Which of the following conclusions is most appropriate about the ppt?

Following two statements are providedStatement-I: Certain chlorides do not show positive response to chromyl chloride test.Statement-II: Chromyl chloride test is positive for Cr3+ ions.Statement-I and statement-II both are wrongStatement-I is wrong and statement-II is correctStatement-I is correct and statement-II is wrongStatement-I is correct and statement-II is correct explanation of statement-I

Take about 1g solid NaCl in a clean anddry test tube and set up the apparatus asshown in Fig. 2.4.n Add some concentrated sulphuric acid tothe test tube.n What do you observe? Is there a gas comingout of the delivery tube?n Test the gas evolved successively with dryand wet blue litmus paper.n In which case does the litmus paper changecolour?n On the basis of the above Activity, what doyou infer about the acidic character of:(i) dry HC

A student found this information about hydrogen.(a) (i) The student repeated Boyle’s experiment using iron and dilute sulfuric acidState two observations that he could have made1.2.(iii) Complete the word equation for this reaction.Iron + sulfuric acid → +(b) Balance the equation for the complete combustion of hydrogen.H2 + O2 → H2O(c) To show that the liquid produced by burning hydrogen was pure water, a student carried out achemical test and a physical test.(i) The chemical test involves adding a few drops of the liquid to a sample of anhydrous copper(II) sulfate. State the colour change observed.Initial colourFinal colour(ii) Place a cross (  ) in one box to show the formula of the compound formed in this chemical test. A Cu(OH ) 2 B CuSO4 C CuSO4H2O D CuSO4 . 5H2O(iii) The physical test involved measuring a property of the liquid.State a suitable physical property and give the value for pure water.Physical propertyValue(c) (i) suggest what property of hydrogen makes it suitable for filling balloons.(iii) Helium is now used instead of hydrogen to fill balloons.State the property of helium that makes it more suitable than hydrogen for filling balloons.(d) Write an equation, including state symbols, to show the process that occurs when hydrogen isliquefied.Ammonium chloride contains oppositely charged ions(a) State the formula of each ionPositive ionNegative ion(b) (i) Describe a chemical test to show that a substance contains ammonium ions.(ii) describe a chemical test to show that a substance contains chloride ions.(c) Ammonium chloride decomposes when heated:NH4CI(s) ⇄ NH3(g) + HCI(g)What does the ⇄ symbol indicate about the reaction?(d) The reaction between ammonia and hydrogen chloride can be used to illustrate diffusion withthe following apparatus.After a few minutes, a white solid appears inside the tube(i) Identify the white solid(ii) What does the diagram show about the speed of the ammonia molecules compared to thespeed of the hydrogen chloride molecules?(e) State the main hazard when using concentrated hydrochloric acid in the experiment in (d)suggest one precaution you could use to minimise this hazard.HazardPrecaution