<span><u>Answer</u>
c). random internal motion of atoms and molecules.
<u>Explanation </u>
Diffusion is the movement of particles from a region of high concentration to region of low concentration. The rate of diffusion can be increased by increasing amount of temperature but this is not its primary cause. Diffusion is primarily caused by movement of molecules or atoms in a substances. Form the choices given, the correct answer is c. random internal motion of atoms and molecules.
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From the concept of optics on a curvature of a spherical mirror, the proportion for which the focal length is equivalent to half the radius of curvature is fulfilled. Mathematically this is

Here,
f = Focal Length
R = Radius
Rearranging to find the radius we have,

Replacing with our values,
R = 2(13.8cm)
R = 27.6cm
Therefore the radius of the spherical surface from which the mirror was made is 27.6cm
Answer:
The change that has to take place inside the power cord in order for the device to function properly include;
The changing of the alternating current (AC) from the electrical outlet to the direct current having a specific voltage and current value with which the device can be powered
Explanation:
A battery powered device makes use of direct current (DC) electric power from a battery, while the power normally given out at an electrical outlet comes as an alternating current (AC) electric power source.
The power cord for battery-powered device, also known as an AC/DC adapter, that allows them to be plugged into electrical outlets converts the AC electric current it obtains from the electrical outlets to DC electrical current of the appropriate voltage and amperage that the device can make use of for electric power to function and for charging the battery which is the power source for the device
Therefore, the change that has to take place in the power cord is the conversion of the electric outlet alternating current (AC) voltage and amperage values, into direct current (DC) of the required voltage and current for the device