Exam 2: The Chemical Context of Life

Figure 2.2 Refer to Figure 2.2 (first three rows of the periodic table). If life arose on a planet where carbon is absent, which element might fill the role of carbon?

If the pH of a solution is decreased from pH 8 to pH 6, it means that the

The atomic number of nitrogen is 7. Nitrogen-15 is heavier than nitrogen-14 because the atomic nucleus of nitrogen-15 contains how many neutrons?

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by

Water molecules are able to form hydrogen bonds with

In what way are elements in the same column of the periodic table the same?

Carbonic acid (H2CO3) serves as a buffer in human blood. Carbonic acid is a weak acid that dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus, H2CO3 ↔ HCO3- + H+ A decrease in blood pH would result in

Which of the following statements about buffer solutions is true?

Figure 2.1 Which of the following best describes the relationship between the atoms described in Figure 2.1?

If an atom of sulfur (atomic number 16) were allowed to react with atoms of hydrogen (atomic number 1), which of the following molecules would be formed?

About 20-25% of the 92 natural elements are known to be essential to life. Which four of these elements make up approximately 96% of living matter?

CO₂ absorbed by the oceans combines with water to form H2CO3. Which of the following will result from increasing the concentration of H2CO3 in the oceans?

Sulfur (atomic number 16) will have chemical properties most similar to

The atomic number of sulfur is 16, which indicates that a sulfur atom contains

Which of the following molecules contains the most polar covalent bond?

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by all organisms?

A covalent bond is formed by

What is the pH of a 1-millimolar NaOH solution?

Consider two solutions: solution X has a pH of 4; solution Y has a pH of 7. From this information, we can reasonably conclude that

One liter of a solution of pH 4 has how many more hydrogen ions (H+) than 1 L of a solution of pH 9?