If an atom has 28 protons and 29 neutrons, what is the mass?

Which statement accurately describes the relationship between air pressure, air density, or altitude? as altitude increases, pressure increases.as altitude increases, air density increases.air pressure and density are lowest at sea level.denser air exerts more pressure than less dense air.

Select the correct answer. when carbon dioxide dissolves in water, it sometimes reacts with water to form carbonic acid as in this balanced equation: co2 + h2o → h2co3. if 495 milliliters of carbon dioxide at 25°c and 101.3 kilopascals reacts with excess water, what is the theoretical yield of carbonic acid? use the periodic table and the ideal gas resource a. 0.889 g b. 1.10g c. 1.27g d. 2.02g what's the answer! quick!

Answer asap need by wednesday morning explain how a buffer works, using an ethanoic acid/sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.