How would you obtain a sol of Agl, the p...

How would you obtain a sol of Agl, the particles of which migrate toward cathode under the electric field ?

By adding little excess of `KI` to `AgNO_(3)` solution

By adding little excess of `AgNO_(3)` to `KI` solution

By mixing equal volumes of `0.010 M AgNO_(3)` and `0.010 M KI`

None of these

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The correct Answer is:

We want to prepare sol of Agl having positively charged particles, so a little excess of `Ag^(+)` should be added to `KI`.

The colloidal particles are electrically charged as a indicated by their migration towards cathode or anode under the applied electric field. In a particular colloidal system, all particles carry either positive charge or negative charge. The electric charge on colloidal particles orginate in several ways. According to preferential adsorption theory, the freshly obtained precipitate particles adsorb ions from the dispersion medium, which are common to their lattice and acquire the charge of adsorbed ions. For example, For example, freshly obtained Fe(OH)_(3) precipitated is dispersed, by a little FeCl_(3) , into colloidal solution owing to the adsorption of Fe^(3+) ions in preference. Thus sol particles will be positively charged. In some cases the colloidal particles are aggregates of cations or anions having ampiphilic character. When the ions posses hydrophobic part (hydrocarbon end) as well as hydrophilic part (polar end group), they undergo association in aqueous solution to form particles having colloidal size. The formation of such particles, called micelles plays a very important role in the solubilization of water insoluble substances, (hydrocarbon, oils, fats, grease etc.). In micelles, the polar end groups are directed towards water and the hydrocarbon ends into the centre. The charge on sol particles of proteins depends on the pH. At low pH, the basic group of protein molecule is ionized (protonated) and at higher pH (alkaline medium), the acidic group is ionized. At isoelectric pH, characteristic to the protein, both basix and acidic groups are equally ionized. The stability of colloidal solution is attributed largely to the electric charge of the dispersed particles. This charge causes them to be coagulated or precipitated. On addition of small amount of electrolytes, the ions carrying oppiste charge are adsorbed by sol particles resulting in the neutralization of their charge. When the sol particles either with no charge or reduced charge, come closer due to Brownian movement, they coalesce to form bigger particles resulting in their separation from the dispersion medium. This is what is called coagulating or precipitation of the colloidal solution. The coagulating power of the effective ion, which depend on its charge, is expressed in terms of its coagulating value, defined as its minimum concentration (m mol/L) needed to precipitate a given sol. How would you obtain a sol of AgI, the particles of which migrate towards cathode under the electric field?

By adding little excess of KI to `AgNO_(3)` solution

By adding little excess of `AgNO_(3)` to KI solution

By mixing equal volumes of 0.010 M `AgNO_(3)` and 0.010 M KI

None of the above

if both the statement are TRUE and STATEMENT -2 is the correct explanation of STATEMENT - 1

If both the statement are STATEMENT -2 is NOT the correct explanation of STATEMENT -1

If STATEMENT -1 is TRUE and STATEMENT is FALSE

If STATEMENT -1 is FALSE and STATEMENT -2 is TRUE

`K_(2)SO_(4)`

`Na_(3)PO_(4)`

`K_(4)[Fe(CN)_(6)]`

`NaCl`