Some amount of dichloromethane ( CH _ 2 Cl _ 2 ) is added to 671 ....

Molarity = \dfrac{mole}{VolumeinL} = \dfrac{mass / Molarmass}{VolumeinL}$</p><p>$2 . 6 \times {10}^{- 3} = \dfrac{x / 85}{0 . 67141}$</p><p>$x = 0 . 148g$</p><p>The number of ppm$= \dfrac{massofsolute}{massofsolution} \times {10}^{6}$</p><p>Mass of solution = density of solution$\times$Volume of solution</p><p>$DCM$in ppm$= \dfrac{0 . 148}{1 . 49 \times 671 . 141} \times {10}^{6}$</p><p>$= 148ppm.