Min tapes a piece of string to each of two ping-pong balls. he hangs the balls so that they are close to one another but do not touch. later, he finds that they have pulled together. they are now touching. what could explain why two balls are now touching?

a) they have both lost their charges

b) they have gained opposite charges

c) they have both gained a positive charge

d) they have both gained a negative charge

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.

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.

How many moles of sulfur dioxide are produced when 4.38 moles of oxygen completely react with iron (iv) sulfide