Questions

Protons carry a positive electrical charge, electrons carry a negative electrical charge and neutrons carry no electrical charge at all. The protons and neutrons cluster together in the central part of the atom, called the nucleus, and the electrons 'orbit' the nucleus.

Hamburg, Germany, is located on the river Elbe at the point where it meets the Bille and Alster rivers. The canals, rivers and streams within the city are crossed by a total of 2,302 bridges-more than the cities of Vanice and Amsterdam combined.

- Process management

- Main memory management

- File management

- I/O system management

- Secondary storage management

- Networking

- Protection system

- Command interpreter system

The logic in this puzzle is summing the result of [subtraction of upper two digits] & [addition of lower two digits] 

Hence, the result is  

(5 - 3) + (2 + 8) = 2 + 10 = 12.

Greek, demotic Egyptian and hieroglyphics.

Methane is the main component of biogas and natural gas.