Choose the CORRECT statement. Question 18 options:

Water is more dense when it is a liquid than when it is a solid.

The production of heat or light is evidence of a physical change.

Paper has been changed chemically when it is torn into pieces.

Particles of matter move more quickly when their temperature gets cooler.

Alarge marble is dropped in a graduated cylinder with 35ml of water in it. the water level increases to 49ml. what is the volume of the marble

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 the mass of silver needed to react with chlorine to produce 126g if silver chloride?