Which statement is true for most chemical reactions?
an energy change occurs during the breaking and forming of bonds.
the internal energy of the system increases during a reaction.
energy is released during the formation of reactants.
the enthalpy of the products is higher than the enthalpy of the reactants.

Which of the following is true for the actual yield of a reaction? it is always calculated as a ratio. it is the yield from the excess reactant. it is the yield from the limiting reactant. it is always less than the theoretical yield.

Why are pipes bursting in the in extremely cold weather?

Look at the spectrums of a star moving towards earth and a motionless star. which of these is a correct inference that can be draw from the observation of the two spectrums? (2 points) the spectrum of a motionless star is difficult to be viewed separately using oridinary telescopes. the spectrum of a motionless star is identical to the spectrum of a star which moves towards earth. the spectrum of a star shifts towards the red region when the star moves towards earth. the spectrum of a star shifts towards the blue region when the star moves towards earth.