Papers included in this bank - ASKnLearn

SAJC/PRELIM2009/P1/Q40Compound Q, with molecular formula C 6 H 12 , was reacted with acidified potassiummanganate(VII) and the resultant mixture obtained was colourless. The mixture wasthereafter distilled to form distillate R and residual solution S.Distillate R is able to form a yellow precipitate with alkaline aqueous iodine.Residual solution S reacts with sodium carbonate to form a colourless gas.Which of the following statements are true?1 Compound Q will decolourise aqueous bromine2 Distillate R can form an orange precipitate with 2,4-dinitrophenylhydrazine3 Residual solution S can form white fumes with PCl 5 .SRJC/PRELIM2009/P1/Q37Which of the following compound(s) forms a yellow precipitate when warmedwith alkaline aqueous iodine?1 butan-2-ol2 1-phenylethanol3 2-phenylethanolSRJC/PRELIM2009/P1/Q38Which of the following reagents can be used to distinguish betweenC 6 H 5 CHO and C 6 H 5 COCH 3 ?1 Aqueous [Ag(NH 3 ) 2 ] +2 Alkaline solution of iodine3 2,4-dinitrophenylhydrazineSRJC/PRELIM2009/P1/Q39It has been noted that prolonged exposure of wine to the atmosphere willresult in the wine becoming “vinegary”. Therefore, wineries attempt toprevent such exposure by storing the wine in a mixture of carbon dioxideand nitrogen.How does this mixture prevent the “vinegary” taste from occurring?1 Oxidation of ethanol into ethanoic acid will be prevented.2 The acidity of the wine will be decreased.3 The amount of carbon dioxide dissolved in the wine will be increased.© SAJC Chemistry Unit 2009 110