Answer:
Option (D) is definitely the answer.
Explanation:
Before going further, it is important to know what buffers and pH represent, which are keywords to answering this question.
Buffers is a special solution that can withstand or resist changes due to pH levels which may be as a result of an introduction of acidic or basic components into the blood. In other words, they maintain the stability of pH level in the human blood.
pH blood levels on the other hand, can be grouped into three: acidity, neutrality and alkalinity. Using a pH scale, one can determine its current level. In the human blood the pH level is near neutral and needs to be on a level near 7.4 in order to avoid a high rise or a drastic fall even if acidic or basic components come in or departs the blood stream.
Therefore, if one of the buffers that contributes to pH stability in human blood is carbonic acid, which is as a result of a combination of carbon dioxide and water in the blood stream. On getting to the lungs it is converted to water and subsequently released as waste. Maintaining this stability will definitely be to decrease the concentration of carbonic acid and increase that of water instead.
The physical and chemical properties of carbon depend on the crystalline structure of the element. Its density fluctuates from 2.25 g/cm³ (1.30 ounces/in³) for graphite and 3.51 g/cm³ (2.03 ounces/in³) for diamond. The melting point of graphite is 3500ºC (6332ºF) and the extrapolated boiling point is 4830ºC (8726ºF).
Explanation:
1) If we have 1/2 OWLs of Snicker bars, then number of items or Snicker bars :
1 OWL = 7 items (given)

We have 3.5 Snickers bars.
2) If we have 100 OWLs of pencils, then number of items or pencils :
1 OWL = 7 items (given)

We have 700 pencils.
3) If we have 2 OWLs of iron atom, then number of iron atoms :
1 OWL = 7 items (given)
of iron
We have 14 atoms of iron.