Opening a pdf on Ubuntu on WSL

I'm using Ubuntu 20.04 with WSL2 in Windows 10.I need to open a file Rplot.pdf on Ubuntu.

I've tried:

First:

xdg-open Rplots.pdf

I got:

Error: no "view" mailcap rules found for type "application/pdf"

Next:

gio open Rplots.pdf

I got:

(gio open:343): GLib-GIO-CRITICAL **: 10:06:22.333: g_dbus_connection_flush: assertion 'G_IS_DBUS_CONNECTION (connection)' failed xterm: Xt error: Can't open display: xterm: DISPLAY is not set