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Q297) In the standardization of Na2S2O3 using K2Cr2O7 by iodometry, the equivalent weight of k2Cr2O7 is [IIT screening 2001]




SOLUTION

in iodometry, KI reacts with K2Cr2O7 in acidic medium to give I2 which is titrated against N2S2O3
K2Cr2O7 + 7H2SO4 + 6KI → 4K2SO4 + Cr2(SO4)3 + 3I2
One mole K2Cr2O7 give three mole I3
2Na2S2O3 + I2 → Na2S4O6 + 2NaI
Thus one mole I2 reacts with 2 mole Na2S2O3
Thus one mole of K2Cr2O7 liberate iodine which reacts with six moles of Na2S2O3
Thus For one 1M Na2S2O3 (1/6 mole) of K2Cr2O7 is required
Answer: (b)


Q298) Elements which generally exhibit multiple oxidation states and whose ions are usually coloured are [ MP PMT 2000[




SOLUTION


Answer: (c)


Q299) In the extraction of iron, slag is produced which is .. [ CPMT 2000]



SOLUTION


Answer:(d)



Q300) The compound that is soluble in water .. [ JIPMER 2000]



SOLUTION

AgF have maximum ionic character than other other halogens of Ag. Solubility decreases down the group
Answer: (a)


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