An electromagnet is the most powerful type of magnet there is. It is a magnet with a current running through it that can be turned on and off .Why might it be useful to be able to turn the electromagnet on and off? to control the strength of the magnet

to reduce wearing out of the magnet over time

to latch onto and let go of objects

to not waste electricity

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.

If an area has high air pressure and low humidity, what type of weather will it most likely have? plz !

The arrangement of particles is most ordered in a sample of