The answer is A 

In the depletion layer, electrons combine with holes producing charge density so that region is depleted of charge carriers  but it has charge density .

Conclusion: Neutral but still having non zero charge density .

Matter is anything that possesses mass, occupies space and may be perceived through one or more senses.

                           The physical divisions of matter are:

1. Solid : Solid matter is composed of tightly packed particles. A solid will retain its shape; the particles are not free to move around.

2. Liquid : Liquid matter is made of more loosely packed particles. It will take the shape of its container. Particles can...

Here, f: A—>B

f(x)= (x-1)/(x+2)  ;  x   -2 

A= {-1,0,1,2,3,4}

B= {-2,1,-1/2,0,1/2,1/4,2/5}

Range = {-2,-1/2,0,1/4,1/2,2/5}

As range is not equal to codomain so the given function is not bijective. 

We can make it bijective by omitting {1} from set B 

At dawn and dusk, large amount of blue and violet light(shorter wavelength) has been scattered so, the light that is recieved by an observer is mostly of a longer wavelength and therefore appears to be red.