Change to a new workspace: Ctrl-Alt ← / → / ↑ / ↓
Place window to a new workspace: Ctrl-Alt-Shift ← / → / ↑ / ↓
As Omer Akram said, the Ctrl-Alt number shortcuts are currently bound to window movement, so the most logical keys for the functionality you are requesting are already taken.
@ Jamu Kakar; the current shortcuts are:
Change to a new workspace: Ctrl-Alt ← / → / ↑ / ↓
Place window to a new workspace: Ctrl-Alt-Shift ← / → / ↑ / ↓
As Omer Akram said, the Ctrl-Alt number shortcuts are currently bound to window movement, so the most logical keys for the functionality you are requesting are already taken.