The stage of cell division in which paired homologous chromosomes get shortened and thickened is prophase I of meiosis. During this stage, the chromosomes condense and become visible as distinct structures, allowing for the homologous chromosomes to pair up and exchange genetic material through a process called crossing over. The shortening and thickening of the chromosomes during prophase I is important for proper alignment and separation of the homologous chromosomes during subsequent...

a)When silver nitrate comes in contact with skin, it is reduced to white color metallic silver.In most cases, a black stain appears due to formation of finely divided silver which has black color.

The black color is due to the decomposition of the Ag+ ion into Ag, silver. Silver nitrate will slowly decompose with the silver ion reverting to elemental silver. The microscopic particles of silver are so small that they absorb light instead of reflecting it, and so appear black, instead of silver....

Yes, a vector which has zero magnitude is also a vector in case of two vectors travelling in opposite directions with equal magnitudes. At this case, the resultant vector has zero magnitude but it is still a vector. We call it a null vector.

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.