Water molecules have a polarity, which allows them to be electrically attracted to other water molecules and other polar molecules by weak chemical bonds known as view available hint(s) water molecules have a polarity, which allows them to be electrically attracted to other water molecules and other polar molecules by weak chemical bonds known as hydrogen bonds polar covalent bonds van der waals interactions ionic bonds nonpolar covalent bonds

Water molecules have a polarity, which allows them to be electrically attracted to other water molecules and other polar molecules by weak chemical bonds known as hydrogen bond.

The polarity of water (H₂O) molecules arises due to the effective difference of electronegativity between the atoms present in the molecule, i.e. hydrogen and oxygen.  

We know, oxygen is highly electronegative element and hydrogen is electropositive. So there generates partial positive (δ+) charge on hydrogen atom and partial negative charge (δ-) on oxygen atom as shown in the figure (1).  

So in solution this positive charge on hydrogen atom attract the negatively charged ion to itself and form a weak bond or interaction which is called hydrogen bond. There remains hydrogen bond between the water molecules itself as the oxygen atom possess negative charge. The hydrogen bond interaction between the water molecules are shown in figure (2).

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.

you did not give any options thus this is the best answer i can give to you with this little information you have given

> they are both natural and not man made

> they can be tracked and predicted by the right tools

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