Two specific examples of radioactive isotopes being used as “spies”

Carbon-14  in photosynthesis and Florbetapir (18F) in PIB of Alzheimer's disease.

Explanation:

These radioactive isotopes known as the biological spies as they tell or mark the presence or activity of a particular atom to the scientists in living beings.

For instance,

1. the process of photosynthesis can be understood by observing the radioactive isotope Carbon-14 from taking the carbon dioxide to the generation of glucose molecule by molecule process.

2. A protein that is deposited in people with Alzheimer's disease, called beta-amyloid. It is bind with another protein known as PIB, which contains  Florbetapir (18F) a radioactive isotope. It gives an idea about the location of PIB and deposits in amyloid to try to eliminate the protein deposits and check the effect of medication.

water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.