IIT-JEE 2010 · Paper 1 · Chemistry Q23

ChemistryInteger+3Question 23 of 84

Amongst the following, the total number of compounds whose aqueous solution turns red litmus paper blue is

KCN, $\ce{K2SO4}$ , $\ce{(NH4)2C2O4}$ , NaCl, $\ce{Zn(NO3)2}$ , $\ce{FeCl3}$ , $\ce{K2CO3}$ , $\ce{NH4NO3}$ , LiCN

Your answer

Answer and worked solution

Official answer: 3

Red litmus turns blue in basic solutions: salts of a strong base with a weak acid.

KCN, LiCN: cyanide hydrolyses, basic. Yes, yes.
$\ce{K2CO3}$ : carbonate hydrolyses, basic. Yes.
$\ce{K2SO4}$ , NaCl: neutral.
$\ce{(NH4)2C2O4}$ : weak acid-weak base salt, roughly neutral (slightly acidic).
$\ce{Zn(NO3)2}$ , $\ce{FeCl3}$ , $\ce{NH4NO3}$ : acidic.

Answer: 3

Topics:Hydrolysis of salts

IIT-JEE 2010 · Paper 1, Chemistry question 23