Questions

W is the symbol for chemical element Tungsten or Wolfram.

It is used in making filaments of bulbs.

Salivary glands of man are 3 pairs = 6. They are one pair of parotid glands, one pair of submaxillary or submandibular glands and one pair of sublingual glands.

Sodium chloride:

The solubility rules tell you that all halides are soluble with the exception of those formed with siver, mercury, and lead ions. Since this is not the case here, sodium chloride will be soluble.

Silver nitrate:

It is soluble because all nitrates are soluble, without exception.

Potassium sulfate:

It is soluble because all sulfates are soluble with the exception of those formed with silver, calcium, barium, mercury, lead, and strontium ions.

Copper (II) hydroxyde:

It is insoluble because all hydroxides are insoluble with the exception of those formed with alkali metal ions and barium.

The process by which bacteria convert nitrogen gas (N2) into ammonia (NH3) is called Nitrogen Fixation.

The conversion of nitrogen from one form to another in the nitrogen cycle is carried out primarily by Nitrogen Fixing Bacteria such as Azotobacter.