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Class 12 Chemistry Chapter 1 Solutions Important Questions | CBSE Board 2020 Quick Revision | Part 2

Class 12 Chemistry Chapter 1 Solutions Important Questions | CBSE Board Quick Revision | Part 1

Hydroxylamine reduces Fe^(3+) accoeding to the following reaction: 2NH_2OH+4Fe^(3+)toH_2O+4Fe^(2+)+4H^(o+)+N_2O Fe^(2+) produced is is estimated by titration with KMnO_4 solution A 10 mL sample of NH_2OH is diluted to 1000 mL. 50 " mL of " this diluted sample is boiled with excess of Fe (III) solution. The resulting solution required 12 " mL of " 0.02 M KMnO_4 for complete oxidation. Determine the strength of NH_2OH .

12. g of an impure sample of arsenious oxide was dissolved in water containing 7.5 g of sodium bicarbonate and the resulting solution was diluted to 250 mL . 25 mL of this solution was completely oxidised by 22.4 mL of a solution of iodine. 25 mL of this iodine solution reacted with same volume of a solution containing 24.8 g of sodium thiosulphate (Na_(2)S_(2)O_(3).5H_(2)O) in one litre. Calculate teh percentage of arsenious oxide in the sample ( Atomic mass of As=57 )

A sample (5.6g) containing iron is completely dissolved in cold dilute HCl to prepare a 250ml of solution. Titration of 25.0ml of this solution requires 12.5ml of 0.03M KMnO_4 solution to reac the end point. Number of moles of Fe^(2+) present in 250ml solution is Xxx10^(-2) (consider complete dissolution of FeCl_2 ). The amont of iron present in the sample is y% by weight Assume: KMnO_4 reacts with Fe^(2+) in the solution Use: Molear mass of iron as 56 gmol^(-1) The value of X is------.

A sample (5.6g) containing iron is completely dissolved in cold dilute HCl to prepare a 250ml of solution. Titration of 25.0ml of this solution requires 12.5ml of 0.03M KMnO_4 solution to reac the end point. Number of moles of Fe^(2+) present in 250ml solution is Xxx10^(-2) (consider complete dissolution of FeCl_2 ). The amont of iron present in the sample is y% by weight Assume: KMnO_4 reacts with Fe^(2+) in the solution Use: Molear mass of iron as 56 gmol^(-1) The value of is------.y

Air sample from an industrial town, heavily polluted by CO_(2) was collected and analyzed . In one anaylsis , 56L of air measured at 1 atm and 273 K was passed through a 250 mL of 0.025 M NaOH solution , where CO_(2)(g) was absorbed completely . 25 mL of the above solution was then treated with excess of BaCl_(2) solution where all the carbonate was precipitated as BaCo_(3)(s) . The solution was filtered off and the filtrate required 25 mL of a 0.005 MHCl solution for neutralization. Weight (in milligrams ) of precipitate BaCO_(3)(s) obtained from the 25 ml of test solution was: [Atomic weight :Ba =137, C=12, O=16]