$3.$ What color change indicates the end point of the EDTA titration in water hardness estimation?a$)$ Yellow to redb$)$ Pink to colorlessc$)$ Blue to colorlessd$)$ Green to blueWhich of the following methods is NOT used for softening hard water?a$)$ Distillationb$)$ Reverse osmosisc$)$ Ion exchanged$)$ FiltrationWhat is the purpose of softening hard water?a$)$ To reduce its pHb$)$ To remove dissolved mineralsc$)$ To increase its electrical conductivityd$)$ To improve its tasteWhich ion exchange resin is commonly used in water softening systems?a$)$ Sodium chlorideb$)$ Potassium chloridec$)$ Sodium zeolited$)$ Potassium zeolite