The number of different elements found in the universe is closest to
a. 12.
b. 24.
c. 48.
d. 100.
e. 192.
Answer: D
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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