$5.$ Which of the following statements about hard water is true?

a$)$ Hard water lathers easily with soap

b$)$ Hard water contains low levels of calcium and magnesium ions

c$)$ Hard water causes scaling in pipes and appliances

d$)$ Hard water has a soft texture on the skin

Which of the following methods is NOT used for the determination of water hardness?

a$)$ Gravimetric method

b$)$ Conductivity method

c$)$ EDTA titration method

d$)$ Spectrophotometric method

What is the main objective of adding phosphates to boiler water?

a$)$ To reduce scale formation

b$)$ To increase corrosion

c$)$ To improve heat transfer

d$)$ To decrease pH

What is the purpose of using pH control agents in boiler water treatment?

a$)$ To maintain alkaline conditions

b$)$ To increase dissolved oxygen levels

c$)$ To accelerate corrosion

d$)$ To promot