What solution has a pH of 7?
A. Aniline
B. Pyridine
C. Pure water
D. Sodium hydroxide
A pH of 7 is a neutral solution, which is how pure water is classified. Researchers can determine the strength of an acid or a base by measuring the pH of a solution. The pH value describes how acidic or basic a solution is. On pH scale, shown below, if the number is less than 7 the solution is acidic. A pH greater than 7 means the solution is basic. When the pH is exactly 7, the solution is neutral.
Therefore, the Correct Answer is C.
More Questions on TEAS 7 Science
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Q #1: Which of the following atoms is a cation?
A. 14 protons, 14 neutrons, 18 electrons
B. 34 protons, 45 neutrons, 36 electrons
C. 35 protons, 44 neutrons, 35 electrons
D. 82 protons, 125 neutrons, 78 electrons
Answer Explanation
Because it has more protons than electrons, this atom has a positive charge and can be classified as a cation. When a metal such as sodium reacts to become stable, it loses its valence electrons. At first, it is a neutral atom with 11 protons and 11 electrons. When it loses an electron, the number of protons does not change, and the atom has 11 protons and 10 electrons. Because there is one more positively charged proton, a cation forms. A cation is an ion with a net positive charge.
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Q #2: An intracellular chemical signal can be produced in the cell membrane. Once it is produced, where does it go?
A. To a different cell
B. To another part of the same cell
C. To a region right outside the cell
D. To an area with a high ion concentration
Answer Explanation
There are two major types of receptor molecules that respond to an intercellular chemical signal:
- Intracellular receptors: These receptors are located in either the cytoplasm or the nucleus of the cell. Signals diffuse across the cell membrane and bind to the receptor sites on intracellular receptors, of the same cell.
- Membrane-bound receptors: These receptors extend across the cell membrane, with their receptor sites on the outer surface of the cell membrane. They respond to intercellular chemical signals that are large, water-soluble molecules that do not diffuse across the cell membrane.
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Q #3: Blood oxygen levels are most likely low when blood _____.
A. leaves the aorta
B. fills the right atrium
C. reaches body tissues
D. flows through arteries
Answer Explanation
Blood continually flows in one direction, beginning in the heart and proceeding to the arteries, arterioles, and capillaries. When blood reaches the capillaries, exchanges occur between blood and tissues. After this exchange happens, blood is collected into venules, which feed into veins and eventually flow back to the heart’s atrium. The heart must relax between two heartbeats for blood circulation to begin.
Two types of circulatory processes occur in the body:
Systemic circulation
- The pulmonary vein pushes oxygenated blood into the left atrium.
- As the atrium relaxes, oxygenated blood drains into the left ventricle through the mitral valve. 3. The left ventricle pumps oxygenated blood to the aorta.
- Blood travels through the arteries and arterioles before reaching the capillaries that surround the tissues.
Pulmonary circulation
- Two major veins, the Superior Vena Cava and the Inferior Vena Cava, brings deoxygenated blood from the upper and lower half of the body.
- Deoxygenated blood is pooled into the right atrium and then sent into the right ventricle through the tricuspid valve, which prevents blood from flowing backward.
- The right ventricle contracts, causing the blood to be pushed through the pulmonary valve into the pulmonary artery.
- Deoxygenated blood becomes oxygenated in the lungs.
- Oxygenated blood returns from the lungs to the left atrium through the pulmonary veins.
