How many grams of F2 are needed to react with 12.9 g of NH3?

Express your answer with the appropriate units.

Ionic compounds are made of ions, and yet the overall charge of an ionic compound is neutral. why?

If two atoms are bonded to a central atom with no lone pairs, how will they be arranged

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.