Questions

Program counter holds the address of either the first byte of the next instruction to be fetched for execution of the address of the next byte of a multi byte instruction, which has not been completely fetched. In both the cases it gets incremented automatically one by one as the instruction bytes get fetched. Also Program register keeps the address of the next instruction.

Mitochondria which is present in both plant and animal cells supplies energy to the cells and hence called as the powerhouse of the cell.

Tax that uses the same rate for all income levels is proportional tax.

When exposed to certain frequencies of radiation, such as radio waves, the subatomic particles called electrons that orbit an atom's nucleus will "jump" back and forth between energy states. Clocks based on this jumping within atoms can therefore provide an extremely precise way to count seconds.It is no surprise then that the international standard for the length of one second is based on atoms. Since 1967, the official definition of a second is 9,192,631,770 cycles of the radiation that gets an atom of the element called caesium to vibrate between two energy states.

The homework should be checked by the teacher

In the early 20th century, the Balkans were called a "powder keg" because the political situation in the region was very unstable. For a long time, the Ottoman Turks occupied the balkans, and with the rise of nationalism, some balkan states declared independence.