Which group of elements is listed in order of decreasing size? O oxygen, nitrogen, carbon, boron O xenon, krypton, argon, neon O carbon, silicon, germanium, tin O lead, thallium, mercury, gold

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

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.

Aconcentrated solution of ammonia is 14.8m and has a density of 0.899g/l. what is the concentration of ammonia in this solution in weight percent (%w/w)?