Purification and properties of colloids

29 questions on Purification and properties of colloids from the Surface Chemistry chapter: 6 NEET level, 12 JEE Main, 11 JEE Advanced. Each one opens with its answer and solution.

• A freshly prepared Fe(OH)3 sol carries NEET level
• Dialysis is a process used for NEET level
• The Tyndall effect is observed in colloidal sols because the colloidal particles NEET level
• For coagulating a negatively charged As2S3 sol, the most effective ion among the following is NEET level
• Brownian motion of colloidal particles is caused by NEET level
• A protective colloid has a very small gold number. This means that the colloid NEET level
• A freshly precipitated Fe(OH)3 sol is to be coagulated by adding one of the following sodium salts at the lowest concentration. The best choice is JEE Main level
• In an electrophoresis experiment with a Fe(OH)3 sol in one U-tube and a gold sol in another U-tube, the colloidal particles migrate towards JEE Main level
• The coagulation values (in mmol per litre of sol) for an As2S3 sol are NaCl = 51, BaCl2 = 0.69 and AlCl3 = 0.093. Which electrolyte has the greatest coagulating... JEE Main level
• A milky liquid mixes freely with water, conducts electricity well, and a water-soluble dye colours it uniformly. The liquid is an emulsion of the type JEE Main level
• Which statement about electrodialysis is correct? JEE Main level
• Brownian motion of colloidal particles becomes more vigorous when JEE Main level
• Which statement about the Tyndall effect is correct? JEE Main level
• Which of the following are properties of lyophilic sols? JEE Main level
• Which statements about dialysis are correct? JEE Main level
• A 50 mL portion of a sol contains 0.35 M NaCl as impurity. It is dialysed twice, each time against 200 mL of fresh pure water, allowing the salt to equilibrate ... JEE Main level
• In an electrophoresis experiment a sol particle front moves 1.8 mm in 90 s when 120 V is applied across electrodes 30 cm apart. The distance moved is proportion... JEE Main level
• The coagulation value of NaCl for a sol is defined as the concentration of NaCl in the final mixture that just coagulates the sol. For a certain sol it is 50 mm... JEE Main level
• Three sols are tested. Sol X is coagulated by Na3PO4 at a lower concentration than by Na2SO4, which in turn needs a lower concentration than NaCl. Sols Y and Z ... JEE Advanced level
• In an electro-osmosis experiment the particles of a sol are held fixed by a porous diaphragm and the dispersion medium is observed to move towards the anode. Th... JEE Advanced level
• The gold numbers of four protective colloids are gelatin 0.005, haemoglobin 0.03, gum arabic 0.15 and starch 25 (all in mg). Which option correctly gives the or... JEE Advanced level
• Which of the following pairs of application and principle is INCORRECT? JEE Advanced level
• The coagulation values (mmol per litre) of a positively charged sol are NaCl 280, CaCl2 270, Na2SO4 2.4. Which of the following electrolytes should coagulate th... JEE Advanced level
• For sol P the coagulation values (mmol per litre) are NaCl 52, BaCl2 0.69, AlCl3 0.093. For sol Q they are NaCl 120, Na2SO4 4.4, Na3PO4 0.11. Select the correct... JEE Advanced level
• The gold numbers (in mg per 10 mL of a standard gold sol) are gelatin 0.01, gum arabic 0.15 and starch 25. Select the correct statements. JEE Advanced level
• In an electrophoresis experiment the distance travelled by the particles of a negative sol in a fixed time is proportional to the applied voltage divided by the... JEE Advanced level
• The gold number of a protective colloid is the mass in mg that just protects 10 mL of a standard gold sol from coagulation by electrolyte. Protective colloid P ... JEE Advanced level
• A sol contains 0.50 M of an ionic impurity. It is dialysed repeatedly. In each cycle the sol volume V is brought to equilibrium with a fresh pure-water volume o... JEE Advanced level
• The Schulze-Hardy rule can be written in the approximate form: coagulation value is proportional to 1/z^6, where z is the valence of the coagulating ion. For a ... JEE Advanced level