Which of the following forces causes comets to regularly return to the inner solar system after being gone for many years? A. friction
B. magnetism
C. electromagnetic force
D. gravity

The density of an unknown gas at 98°c and 740 mmhg is 2.50 g/l. what is the molar mass of the gas with work showed?

1) this is the structure in the cell nucleus that houses a cell's genetic information

The activation energy for the reaction no2(g)+co2(g)⟶no(g)+co(g) is ea = 300 kj/mol and the change in enthalpy for the reaction is δh = -100 kj/mol . what is the activation energy for the reverse reaction?