What happens to the level of mercury in a mercury barometer when air pressure decreases?

Explanation:

With an increased weight of air above the reservoir, the mercury level rises to a higher level. ... Since the number of air molecules above the area decreases, there are fewer molecules to exert a force on that surface. With a reduced weight of air above the reservoir, the mercury level drops to a lower level

Atmospheric pressure is commonly measured with a barometer.

Explanation:

In a barometer, a column of mercury in a glass tube rises or falls as the weight of the atmosphere changes. ... As the pressure decreases, the amount of oxygen available to breathe also decreases.

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.