What mass of a 4.00% NaOH solution by mass contains 15.0 g of NaOH?

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.

How have the greenhouse gasses increased from the year 2000 to 2018

What is the molar mass of a gas that has density of 2.054 g/l