Amongst the following, the total number of compounds whose aqueous solution turns red litmus paper blue is ___
KCN K2SO4 (NH4)2C2O4 NaCl Zn(NO3)2 FeCl3 K2CO3 NH4NO3
Basic salt solutions will have pH > 7. These will change the colour of litmus paper from red to blue
Here, KCN,K2CO3 and LiCN are the only basic salts. So, the answer will be 3.