JEE Advanced levelOne or more correct optionsDifficulty 3 of 3sc216
Protective colloids P, Q and R have gold numbers 0.02, 0.5 and 25 respectively (mg per 10 mL of gold sol). Select the correct statement(s).
AP is the best protective colloid of the three.
BThe mass of R needed for a given protection is 1250 times that of P.
C2.0 mg of Q just protects 40 mL of the gold sol.
DR is a better protective colloid than Q.
Answer: A, B, C
A smaller gold number means better protection, so P is best (statement 1 correct) and R is worse than Q (statement 4 wrong). 25/0.02=1250 gives statement 2. Q: 2.0/0.5×10=40 mL, so statement 3 is correct.