TOEFL Mock Test 100: Reading Passages
Read the passage below and choose the best answers for the following questions.
Questions and Answers
- 1.
BOND AND ENERGY (1) Atoms combine chemically with one another in one of two ways, that is, they form bonds. Chemical bonds are formed when the outermost electrons are transferred or shared between atoms. When the atoms of two or more different elements combine this way, a compound (such as water) is created. (2) One type of bond is called an ionic bond. This kind of bond is formed when one atom gains electrons while the other atom loses electrons from its outermost level or orbit. Atoms that gain electrons become negatively charged, whereas those that lose electrons become positively charged, each having originally been electrically neutral. The new charged atoms are called ions. Negatively charged ions are attracted to positively charged ions together are ionic bonds. (3) A second type of bond found in many molecules is the covalent bond. In this type of bond, the atoms share electrons to fill their outermost levels. Molecules containing covalent bonds do not dissociate when immersed in water. Four of the most important elements found in cells from this type of bond. They are carbon (C), oxygen (O), hydrogen (H) and nitrogen (N). they constitute about 95% of the materials found in cells. All of the cell’s larger molecules and many of its smaller ones contain such bonds; for example, the formation of the covalent bond between two hydrogen atoms forms the compound hydrogen gas. (4) Another type of bond is hydrogen bond. Hydrogen bonds are very weak bonds and help hold water molecules together by forming a bridge between the negative oxygen atom of one water molecule and the positive hydrogen atoms of another water molecule. Hydrogen bonds also help bind various parts of one molecule into a three-dimensional shape such as a protein molecule like an enzyme. If we measure the amount of energy present between two atoms, we discover that the amount varies as the distance between the atoms changes. SOURCE: Fundamentals of Anatomy and Physiology Second Edition Thomas Asian Edition Question: The word compound in the passage is closest in meaning to
- A.
Requirement
- B.
Ingredients
- C.
Mixture
- D.
Assortment
Correct Answer
C. Mixture -
- 2.
The word those in the passage is referring to
- A.
Electrons
- B.
Atoms
- C.
Ionic bond
- D.
Electricity
Correct Answer
B. Atoms -
- 3.
The word dissociate in the passage is closest in meaning to
- A.
Distance
- B.
Detach
- C.
Associate
- D.
Absorbed
Correct Answer
B. Detach -
- 4.
Look at the four (4) paragraphs that indicate where the following sentence could be added to the passage. “Bonds contain energy, the ability to do work. This results from the interaction of the electrons and the nuclei of the bonded atoms.” Where could the sentence best fit? Choose the number of the paragraph where the sentence should be added.
- A.
4th
- B.
2nd
- C.
3rd
- D.
1st
Correct Answer
A. 4th -
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