4. Some amount of dichloromethane \( CH _{2} Cl _{2} \) is added to \( 671.141 mL \) of chloroform \( \left( CHCl _{3}\right) \) to prepare \( 2.6 \times 10^{-3} M \). Solution of \( CH _{2} Cl _{2} \) (DCM). The concentration of \( DCM \) is \( \qquad \) \( ppm \) (by mass). Given: Atomic mass : \( C =12 ; H : 1 ; Cl =35.5 \) density of \( CHCl _{3}=1.49 gcm ^{-3}[ JEE \) Main, Jan 2023]
