Question

Among cellulose,poly vinyl chloride,nylon and natural rubber the polymer in which the intermoleculer force of attraction is weakest

Answer 1

(A) Na2SO4 (B) CaCl2 (C) Al2(SO4)3 (D) NH4Cl
Sol.: According to Hardy–Schulze rule, the coagulating power of an ion is directly proportional to the magnitude of its charge.
So, For negatively charged Sb2S3 sol, the most effective coagulating agent would be Al2(SO4)3 .
Correct choice: (C)
*2. Given that the abundances of isotopes 54Fe, 56Fe and 57Fe are 5%, 90% and 5%, respectively, the atomic mass of Fe is
(A) 55.85 (B) 55.95 (C) 55.75 (D) 56.06
Sol.: Average atomic mass of an element = ∑AiXi
where Ai and Xi represents the atomic mass and mole fraction of the component in the mixture.
Average atomic mass of Fe =(54×5)+(56×90)+(57×5)/100
= 55.95
Correct choice