Negative siRNA controls are shipped dry as duplexes and should be resuspended in DNAase, RNAase-free water.
The 10 nmol quantity should be resuspended with 100 microliters of water, while the 1 nmol tubes should be resuspended with 10 microliters.
These volumes will result in the buffer being at 1x concentration and the siRNA at a concentration of 100 micromolar (100 pmol per microliter).