drafty single pane windows - sealant?

[Lorena]

Rented house with drafty single pane windows. Some of them are missing bits of pointing (i think that's what it's called) around the frame. Looks like the panes are held in place with a white mass that has fallen off in chunks. Can I just patch up these missing bits by applying a window sealant? If so, which one is recommended?

Also I read elsewhere in this site that absorbent strips can be fixed to windows to prevent condensation. Which type and where in the window please?

Thanks!