Radio waves are primarily used to
image people's bones
absorb harmful radiations
transmit cellular phone signals
detect the location of objects that emit heat

Radio waves are primarily used to transmit cellular phone signals.

Explanation:

A radio wave is a wave in the form of electromagnetic radiation with wavelengths ranging from roughly a thousand kilometers to a millimeter, so in the frequency range of a few hundred Hz to a few hundred GHz. Radio waves are used in communication technology to transfer information from a radio station to one or more receivers. Radio waves were discovered by Heinrich Rudolf Hertz in 1886.

The transmitter transmits via an antenna, whether or not directed, the radio waves that, after propagation through the space, are picked up by the antenna of the receiver. The radio wave serves as a carrier for the information to be transmitted, which is present as a variation in the amplitude (AM) or in the frequency (FM).

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it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.