General Principles and processes of Isolation of Elements
hard

कोलाइड के सम्बन्ध में निम्न में से कौन सा कथन असत्य है ?

A

जब सिल्वर नाइट्रेट विलयन, पोटैशियम आयोडाइ्ड विलयन में मिलाया जाता है तो एक ऋणावेशित कोलाइडी विलयन बनाता है।

B

विलेय की एक ही सान्द्रता पर वास्तविक विलयन की तुलना में कोलाइडी विलयन का हिमांक निम्न होता है।

C

कोलाइडी कण एक साधारण फिल्टर पेपर से हांकर निकल जाते हैं।

D

जब कोलाइडी विलयन में विद्युत अपघट्य की मात्र आधिक्य में डालने पर कोलाइडी कण अवक्षेपित हो जाते हैं।

(JEE MAIN-2018)

Solution

$(a)$ Colloidal particles are so small that they can pass through ordinary filter paper. Also, they cannot be seen with ordinary microscope.

$(b)$ Freezing point of colloidal solution is same as that of true solution at same concentration of a solute. The depression in freezing point is a colloidal property and depends on the number of solute particles and independent of size or shape of solute particles.

$(c)$ When silver nitrate solution is added to potassium iodide solution, a negatively charged colloidal solution is formed due to selective adsorption of $I^-$ ion from the dispersion medium. However, if the order of addition is reversed, i.e, potassium iodide solution is added to silver nitrate solution, due to selective adsorption of $Ag^+$ ion from the dispersion medium, a positively charged colloidal solution is obtained.

$(d)$ When excess of electrolyte is added to colloidal solution, colloidal particle will be precipitated. Although electrolytes in minute quantities are necessary for the stability of colloids, they cause coagulation of disperse phase if present in large quantities.

Standard 12
Chemistry

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