29. What is E for a system which has the following two steps: Step 1: The system absorbs 60 J of heat while 40 J of work are
performed on it.
Step 2: The system releases 30 J of heat while doing 70 J of work.
C. 90 J
A. 110J
B. 100 J
D. Zero

List four observations that indicate that a chemical reaction may be taking place

How do scientists think that gravity affected the formation of our solar system?

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.