A student wants to determine whether an unknown solid is an ionic compound. He puts some in water and finds that it does not dissolve. He says that this proves the solid is ionic. Which best evaluates the student's reasoning?
He is incorrect, because water can dissolve ionic solids.
The test proves nothing, because water dissolves all solids.
He is correct, because polar liquids cannot dissolve ionic solids.
The test proves nothing, because it only shows that the solid is a compound.

Your town is considering building a biodiesel power plant describe at least two advantages and two disadvantages

The ultracentrifuge is an important tool for separating and analyzing proteins. because of the enormous centripetal accelerations, the centrifuge must be carefully balanced, with each sample matched by a sample of identical mass on the opposite side. any difference in the masses of opposing samples creates a net force on the shaft of the rotor, potentially leading to a catastrophic failure of the apparatus. suppose a scientist makes a slight error in sample preparation and one sample has a mass 10 mg larger than the opposing sample. if the samples are 12 cm from the axis of the rotor and the ultracentrifuge spins at 70,000 rpm, what is the magnitude of the net force on the rotor due to the unbalanced samples? ( be thorough on your answer)

Efficiency is the ratio of to for a system a)power in to power in b)power in to power out c) power out to power out d) power out to power in