The name of the commonly used hardness scale is: specific gravity organic mohs inorganic

According to the vsepr theory what is the shape of a molecule that has a central atom valence three other items with no lone pairs of electrons

In the millikan oil drop experiment they determined that every drop had a charge which was a while number multiple of -1.60x10^-19. if a drop has a total charge of -9.60x10^-19 then how many excess electrons are contained within the drop?

When a device is used in a circuit in which the voltage is 81 v the current flowing through the device is 3 a what is the resistance of the device