Which of the following statement is/are correct?
1
One Nephelometry Turbidity Unit (NTU) is equal to the turbidity produced by 1 mg SiO2 dissolved in 1l of distilled water with the test being run according to the scattering principle.
2
One Nephelometry Turbidity Unit (NTU) is equal to the turbidity produced by 1 mg formazine dissolved in 1l of distilled water with the test being run according to the scattering principle.
3
Pseudo-hardness is due to the presence of fluorides in water.
4
Carbonate hardness is equal to a maximum of alkalinity and total hardness.