A. I think I’m that’s what it is
In order to purify ammonia to high purity, two basic methods are used. The older one consists in passing gaseous ammonia containing 80 ppm of impurities under atmospheric pressure through liquid ammonia with dissolved metallic sodium.
A compound machine is that which is composed of two or more simple machines. Simple machines come in 6 basic types: (1) wheel and axle, (2) inclined plane, (3) wedge, (4) pulley, (5) screw, and (6) lever. Among the choices given above, the compound machine is the can opener for it is a combination of a wedge and a lever.
C is correct.
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