Which group of 1A elements are less dense than pure water at 4°C

When applying kirchhoff's rules, one of the essential steps is to mark each resistor with plus and minus signs to label how the electric potential changes from one end of the resistor to the other. the circuit in the drawing contains four resistors, each marked with the associated plus and minus signs. however, one resistor is marked incorrectly. which one is it?

What is the mass of the same rock on the earth

Anybody wanna ? (picture included? )