chemistry model exam for bed and bsc students

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hawassa university model exam model exam 2 for bed and bsc chemistry students 1. student a was doing an experiment to determine the surface tension of an organic liquid using drop count method. the student used an instrument called stalagmometer and counted the number of drops from the fixed (equal) volume of water and organic liquids. three measurements (trials) were done for each liquid and the results are summarized in table below. trial number of drops counted from the fixed volume of liquid water organic liquid 1 36 55 2 34 54 3 36 56 what is the surface tension of organic liquid if the densities of water and the organic liquid are 0.996 and 0.80 and the surface tension of water is? a) b) 3.68 10-2 nm-1 c) 2.410-3 nm-1 d) 6.3 10-3 nm-1 questions from 2-4 is based on the data shown in the table. student b optimized …

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e transistion metals is associated with higher catalytic activity? a. high enthalpy of atomization b. paramagnetic behavior c. colour of hydrate ions d. variable oxidation states 7. which of the following is wrong about either orthotitanic acid, tio2.2h2o or metatitanic acid, tio.h2o? a. tio2.2h2o can be prepared by the reaction of titanyl sulphate (tioso4) with naoh. b. although tio2.2h2o displays amphoteric behavior; it readily dissolves in h2so4 but is insoluble in naoh, indicating that it has a more basic character. c. metatitanic acid, tio2.h2o may be prepared by boiling tio2,2h2o in naoh d. although it is soluble in h2so4, metatitanic acid, tio.h2o is insoluble in naoh. 8. all of the following are correct except a. titanium(iv) compounds can be reduced to titanium (iii) using zn as a reducing agent. b. ti(iv) compounds can be identified using the reaction: tio2+ + h2o2 → ti(o2) + h2o. c. metatitanic acid, tio2.h2o is …

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eated with ki, iodide ion is oxidized to _________ a. a. i2 b.io- c. io2- d. io3- 13. which of the following statements is not correct? a. copper liberates hydrogen from acids b. in its higher oxidation states, manganese forms stable compound with oxygen and fluorine c. mn3+ and co3+ are oxidizing agents in aqueous solution d. ti2+ and cr2+ are reducing agents in aqueous solution 14. in the laboratory, manganese (ii) salt is oxidized to permanganate ion in aqueous solution by a. hydrogen peroxide b. conc. nitric acid c. peroxydisulfate d. dichromate 15. in the group of alkaline earth metals,which elements do not give flame color to the bunsen flame ? a. calcium and strontium b. barium and strontium c. beryllium and magnesium d. calcium and magnesium 16. which of the following is not correct about alkaline earth metals? a. all the alkaline earth metals except beryllium react with …

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n d. extra energy being absorbed and emitted as visible radiation. 20. consider the oxides of giiiia: i. b2o3 ii. al2o3 iii. ga2o3 iv. in2o3 which shows both amphoteric and acidic oxides? a. i and ii b. ii and iii c. iii and iv d. ii and iv 21. identify the correct statement about benzene and cyclooctatetraene. a. benzene has a bent shape and cyclooctatetraene is planar. b. benzene has non-delocalizing six pi-electrons and cyclooctatetraene has eight delocalizing pi-electrons. c. benzene readily undergoes addition reaction where as cyclooctatetraene undergoes electrophilc substitution reaction. d. cyclooctatetraene is non-aromatic compound, and readily decolorize kmno4 and br2 at room temperature whereas benzene doesn’t decolorize bromine at room temperature. e. both compounds belong to the same family; namely aromatic compounds 22. nucleophilic addition is characteristics reaction of ketones and aldehydes. given compounds (a to c), their reactivity orders toward nucleophilic addition reaction are a. a>b>c …

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s and aldehydes? a. reduction of aldehydes and ketones in the presence of reducing reagents such as nabh4 gives secondary and primary alcohols, respectively b. reaction of ketones with grignard reagent (rmgbr) in ether gives secondary alcohols c. oxidation of secondary alcohols can be used to prepare aldehydes d. aldehydes can be oxidized with sodium (or potassium) dichromate in acidic medium to form carboxylic acids containing the same number of carbon atoms e. redox reactions do not exist in biological systems (or living cells) 28. wittig reaction is one of the common reactions of aldehydes and ketones. which one of the following compound is the major product of the reaction shown below? 29. friedel-crafts alkylation of benzene in the presence of alkyl halides and alcl3 (lewis acid catalyst) yields alkyl benzene via electrophilic aromatic substitution reaction. which one of the following statements is true about reaction of benzene with isobutyl …

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hawassa university model exam model exam 2 for bed and bsc chemistry students 1. student a was doing an experiment to determine the surface tension of an organic liquid using drop count method. the student used an instrument called stalagmometer and counted the number of drops from the fixed (equal) volume of water and organic liquids. three measurements (trials) were done for each liquid and the results are summarized in table below. trial number of drops counted from the fixed volume of liquid water organic liquid 1 36 55 2 34 54 3 36 56 what is the surface tension of organic liquid if the densities of water and the organic liquid are 0.996 and 0.80 and the surface tension …

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