The source of heart for a (an) close system is electricity.
A hole, and people die if they fall in there.
If its atomic number is 48, then it has 48 protons in the nucleus
of each atom. Any more mass than that is supplied by the neutrons
that are mixed in there with the protons.
If the mass is 167, and 48 of those are protons, then there are
(167 - 48) = 119 neutrons
in each nucleus.
Is a circuit with both a resistor (R) and a capacitor (C). RC circuits are frequent element in electronic devices. They also play an important role in the transmission of electrical signals in nerve cells.
Hope this helps!