What is the mass number of an atom which contains 21 electrons,21 protons and 24 neutrons

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.

Calculate: select the worksheet tab. this tab you calculate the analyte concentration.  fill in the first set of boxes ("moles h2so4" and "moles naoh") based on the coefficients in the balanced equation. (if there is no coefficient, the value is 1.)  record the appropriate volumes in the "ml naoh" and "ml h2so4" boxes.  record the concentration of the titrant in the m naoh box. click calculate. what is the concentration listed

How might this scientific phenomena be explained? a paper clip floats on water.