Relations of the DCO⁺ J =1-0 gas mass (M_DCO⁺, left column), H₂CO J=3_0,3-2_0,2 gas mass (M_H2CO, center column), and c-C₃H₂ J=3_3,0-2_2,1 gas mass (M_c-C3H2, right column) versus envelope dust mass (M_env) for the sample. In all panels the dash-dotted red line shows the N₂H⁺ gas mass versus envelope dust mass from Paper I as reference. The full sample with no differentiation for multiplicity is shown in the top row. In the other three rows, orange stars indicate multiple protostellar systems, cyan diamonds show binary systems, and gray circles indicate single protostellar systems. Each row represents one of four ways of grouping the sample and their corresponding correlations (see Sect. 4.4). Lines and shaded areas show the linear regression for the data with the corresponding color. Solid lines indicate statistically significant correlations in the subsamples (censored Kendall rank correlation p value of <0.05), while the dashed line shows subsamples with p values of >0.05.