Q6 of 37 Page 1

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Name the substance used as depressant in the separation of two sulphide ores in Froth floatation method.


Froth floatation method of concentration of sulphide ore.


Sulphide ores are preferentially wetted by oils while the gangue is preferentially wetted by water. The ore particles get adsorbed on oil droplets and come to the surface where they can be collected as froth gangue is wetted by water and gets settled down. Eg. It is done for PbS ores.


Depressants help to separate two sulphide ores by selective prevention of froth formation by one ore and allowing the other to come into the froth. NaCN is used as a depressant in order to separate two sulphide ores (ZnS and PbS).


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4

Read the given passage and answer the questions

A Lead storage battery is the most important type of secondary cell having a lead anode and a grid of lead packed with PbO2 as cathode. A 38% solution of sulphuric acid is used as electrolyte. (Density=1.294 g mL-1) The battery holds 3.5 L of the acid. During the discharge of the battery, the density of H2SO4 falls to 1.139 g mL-1. (20% H2SO4 by mass)


The lead storage battery is considered a secondary cell. Why?


 5

Read the given passage and answer the question

A Lead storage battery is the most important type of secondary cell having a lead anode and a grid of lead packed with PbO2 as cathode. A 38% solution of sulphuric acid is used as electrolyte. (Density=1.294 g mL-1) The battery holds 3.5 L of the acid. During the discharge of the battery, the density of H2SO4 falls to 1.139 g mL-1. (20% H2SO4 by mass)


Write the products of electrolysis when dilute sulphuric acid is electrolysed using Platinum electrodes.


 7

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Name the unit formed by the attachment of a base to 1’ position of sugar in a nucleoside.


 8

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Name the species formed when an aqueous solution of amino acid is dissolved in water?