Which of the following substances will cause the least temperature change if the same amount of each substance is added to 1.0 kg of water?
k3po4
cuso4
ch4oh
mgcl2

This is a question based on colligative property

colligative property is a property of solution which depends upon the number of molecules of solute and solvent

It is independent of nature of solute added to a particular solvent

The colligative properties are

a) elevation in boiling point

b) depression in freezing point

c) relative lowering of vapour pressure

d) osmotic pressure

As given we are adding same mount of each substance

Which means that we are adding same moles of each substance

the minimum number of particles will be produced by CH3OH (methanol) hence it will cause least temperature change.

The greatest change will be due to K3PO4

the answer would be b i believe