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 .

It is theoretically possible for a substance to have a negative value of cubical expansivity, which means that the substance would contract rather than expand when the temperature increases. However, it is very rare for a substance to have a negative value of cubical expansivity over a significant range of temperatures.

One example of a substance that has a negative value of cubical expansivity over a limited range of temperatures is water. Water has a positive value of cubical expansivity at...

If one could be a billionaire by following a how-to guide step by step, you'd have already come across it by now. 

Well, the how-to "BE" part is simple; own anything that's worth a billion- an idea, an asset, a skill, anything. It is the how-to reach that milestone that is mystic. Carve your own path to it. 

Once you find the secret (IF there is one), share it on Mattrab :P 

Or maybe don't ;) let others find their own path.

II)Cr2+ is reducing agent as its configuration changes from d4 to d3, when it is oxidized to Cr3+ .The d3 configuration have a half-filled t2g level which is very stable. On the other hand, the reduction of Mn3+ to Mn2+ results in the half-filled (d5) configuration which has extra stability hence Mn3+ acts as oxidizing agent.

The Wheatstone bridge is not suitable for measuring very low resistance because it is based on a ratio of two resistances, and the resolution of the bridge decreases as the ratio approaches 1. This means that the Wheatstone bridge is not accurate enough to measure very small changes in resistance.