11. 1. Calculate the number of water molecule
present in one drop of water which weighs
0.18 g.

6.022×10²¹

Explanation:

First calculate the number of moles

n=m/GFM

n=.018/18

n=0.01moles

Then multiply the number of moles by the molar mass

0.01×6.022×10²³ =6.022×10²¹

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).