Was Serbia and Romania parts of Austrian empire?

Serbia and Romania were not a part of the Austrian Empire. The Austrian Empire was a multi-ethnic empire that existed from 1804 to 1918, and included present-day Austria, Hungary, the Czech Republic, Slovakia, Slovenia, Croatia, Bosnia and Herzegovina, Transylvania, Galicia, and parts of Poland, Italy, and Ukraine. Serbia and Romania were both independent countries during this time period, although Serbia was a tributary state of the Ottoman Empire until 1878 and Romania was a tributary state of the Ottoman Empire until 1881.