The four elements most common in organisms are
a. calcium, iron, hydrogen, and oxygen.
b. water, carbon, hydrogen, and oxygen.
c. carbon, oxygen, hydrogen, and nitrogen.
d. nitrogen, carbon, iron, and hydrogen.
e. phosphorus, water, carbon, and oxygen.
Answer: C
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Small Molecules and the Chemistry of Life
- One mole of a substance contains 6.02 × 1023 molecules. This number is known as _______.
- The amount of heat needed to raise one gram of a substance 1°C is known as _______.
- The water strider skates along the surface of water due to a property of liquids called _______.
- In the equation C6H12O6 ? 6CO2 + 6H2O, C6H12O6 is the _______.
- The attraction between a slight positive charge on a hydrogen atom and the slight negative charge of a nearby electronegative atom is a _______.
- Of the different types of chemical bonds, the strongest bond in biological systems is the _______ bond.
- Molecules that have an unequal distribution of electric charge are called _______ molecules.
- The electronegativity of an atom depends upon the number of _______ and how far the _______ are from the nucleus.
- The molecular weight of glucose (C6H12O6) is _______.
- A _______ is two or more atoms linked by chemical bonds.
- The tendency of atoms in stable molecules to have eight electrons in their outermost shells is known as the _______.
- ______ occurs when one atom, such as 14C, is transformed into another atom, such as 14N, with an accompanying emission of energy.
- The chemical properties of an element are determined by the number of _______ its atoms contain.
- The sum of the atomic weights in any given molecule is called its _______.
- Every atom except for _______ has one or more neutrons in its nucleus.
- Oxygen and carbon are defined as different elements because they have atoms with a different number of _______.
- One dalton is the same as the mass of one _______.
- Solutions that contain buffers tend to resist pH changes because buffers
- Carbonic acid and sodium bicarbonate act as buffers in the blood. When a small amount of acid is added to this buffer, the H+ ions are used up as they combine with the bicarbonate ions. When this happens, the pH of the blood
- The optimum pH for growing strawberries is 6.5, whereas the optimum pH for growing blueberries is 4.5. Therefore, the number of hydrogen ions needed to grow strawberries is _______ times the number needed for blueberries.
- Which of the following has the greatest concentration of hydrogen ions?
- The notation [H+] refers to the
- Acid rain is a serious environmental problem. A sample of rainwater collected in the Adirondack Mountains had an H+ concentration of 10-4 mol/L. The pH of this sample was
- The more acidic of two solutions has
- A substance with a pH of 6.0 contains