Why are certain metalloids useful in today's technological equipment? a. they are brittle and tough. b. they are semi-conductors. c. they have a low melting point. d. they are opaque.

The answer is B.

Metalloids are elements that posses some of the characteristics of non-metals and also some of the characteristics of metals.

The semiconductivity property of metalloids such as Siliconium, Geranium have been leveraged to the maximum and these are used in LCD screens, televisions and many other technological appliances.

probably not the "magnets"in the magnet, so to speak, are thought to be electrons orbiting in shells. vurrent loops two sides to the loop

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.