How many moles of helium gas occupy 22.4 L at 0 degreeC at 1 atm pressure

Why does his teacher ask him to balance the equation by including the correct coefficient

Joe shines white light into a bowl half full of water at an angle of incident of 27.5°. calculate the angle of refraction in the water given the indices of refraction for air and water are 1.00 and 1.36, respectively.

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.