The tip of a match is ignited as it is struck against the matchbox. why is this a chemical change? a. the color of the match tip has changed. b. the match changes size as it burns. c. the tip of the match is flammable and is set on fire. d. the match is melting.

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.

What does a numerical subscript following an element in a chemical formula mean?

Which of these is a density dependent factor? a. epidemic b. earthquake c. drought d. hurricane