PLEASE HELP

Noble gases are commonly used in gas discharge tubes commonly known as "neon signs". What causes the light produced in these signs?

A. excited electrons falling back to the nucleus

B. electrons being excited to higher energy levels then returning to their original energy level

C. gases reacting with the glass of the sign due to being electrified

D. electricity giving the atoms greater vibrational energy

1. suppose a reaction mixture, when diluted with water, afforded 300 ml of an aqueous solution of 30 g of the reaction product malononitrile [ch2(cn)2], which is to be isolated by extraction with ether. the solubility of malononitrile in ether at room temperature is 20.0 g/100 ml, and in water is 13.3 g/100 ml. what weight of malononitrile would be recovered by extraction with (a) three 100-ml portions of ether and (b) one 300-ml portion of ether? suggestion: for each extraction, let x equal the weight extracted into the ether layer. in part (a), the concentration in the ether layer is x/100 and in the water layer is (30 x)/300; the ratio of these quantities is equal to k 20/13.3.

Which of the dna typing techniques do you think you would choose if you had to analyze a dna sample? why?

Identify the lewis base in this balanced equation: fe3+ h2o fe(h2o)63+