In the fig above, M and N are insulated metal spheres in contact. A negatively charged ebonite rod P is I brought near M. When M and N are Separated and the rod is taken away, which of the following statements is correct
A.
both M and N have acquired negative charges
B.
both M and N have acquired positive charges
C.
M has acquired negative charge and N positive charge
D.
N has acquired negative charge and M positive charge
When one arm of a U-tube manometer is connected to a gas supply, the levels of mercury in the two arms of the U-tube is shown in the figure above, if the atmospheric pressure is 76.0cm hg, the gas pressure is
