Which reaction can be used to calculate the enthalpy of formation of a substance? 2 (g)→ (g)+.5 2 (g)
(g)+.5 2 (g)→2 (g)
(g)+2 (g)→3 (g)
2 (g)+.5 2 (g)→2 (l)

The famous scientist galileo galilei did several experiments with sloping planes, which he rolled metal balls down so that he could study motion. by changing the slope, he could study how the speed at which the ball rolled was affected. what was the independent variable in galileo's experiment? a. the speed of the ball b. the slope of the plane c. whether the ball moved d. what the ball was made of

What type of electromagnetic waves does the human eye see as the colors red blue or green a visible light waves b radio waves c infrared waves d microwaves

Use the de broglie's wave equation to find the wavelength of an electron moving at 4.5 × 106 m/s. show your work. note: h= plank's constant (6.62607 x 10-34 j s)