Look at the chlorine residual data during chlorination of wastewater which consists of ammonia, organic matter, and microorganisms.

Chlorine dosage (mg/L)	0.1	0.5	1.0	1.5	2.0	2.5
Chlorine residual (mg/L)	0.0	0.4	0.8	0.4	0.9	1.4

Calculate chlorine dose at the breakthrough point