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Read the text. Then answer the questions choosing the most appropriate variant (7 points)


A snowflake originates from countless water molecules that initially come together in small groups as a result of a weak attractive force between oxygen and hydrogen atoms. The same forces subsequently organize the groups into a frozen molecular crystal, a perfectly organized lattice of molecules. Finally, several molecular crystals join to form a snowflake. Scientists have realized for some time that the forces that assemble molecules into natural crystals can be utilized to produce a variety of important materials. They have determined the structure of more than 90,000 different molecular crystals, the most common examples of which are aspirin and mothballs.

In recent years, researchers have studied how molecules organize themselves to form crystals in the hope of better understanding what types of molecules and what conditions will produce molecular crystals with unusual and useful properties. Scientists are aware that the material properties of a crystal depend in large part on the organization of the molecules in the crystal, yet they know little about the factors controlling the assembly of such crystals.

Synthesizing a molecular crystal is similar to designing a building. Before construction can begin, the architect must specify the shapes and sizes of the girders and the number and placement of the rivets. Similarly, to produce new molecular crystals, chemists must choose molecules of the appropriate sizes and shapes and select the molecular forces that will hold the crystals together. A chemist can normally find many molecules of various shapes and sizes, but the challenge is to find ones that assemble in a predictable manner.

1. According to the passage, a snowflake is formed by

(A) the joining of numerous water molecules

(B) molecular crystals with new and useful properties

(C) the synthesizing of molecular crystals

(D) the attractive force between oxygen and hydrogen

2. According to the passage, water molecules join together as a result of

(A) the unusual and useful properties of molecular crystals

(B) the organization of the molecules in a crystal

(C) a strong force that assembles crystal atoms

(D) an attraction between oxygen and hydrogen atoms

3. By making use of forces that assemble molecules into natural crystals, scientists can

(A) find molecules of various shapes and sizes

(B) determine the structure of different molecular crystals

(C) organize molecules into a perfect lattice

(D) create new and useful materials

4. According to the passage, what reason do researchers have for studying how mole-cules organize themselves to form crystals?

(A) To assemble molecules into natural crystals

(B) To learn how to synthesize molecular crystals

(C) To make aspirin and mothballs

(D) To change the material properties of a crystal

5. According to the passage, what do scientists still need to learn about the organization of molecules?

(A) What determines the material property of a crystal

(B) The molecular forces that hold molecules together

(C) The conditions that produce molecular crystals

(D) The factors controlling the way crystals are assembled

6. To produce new molecular crystals, chemists must choose all of the following EXCEPT

(A) molecules of the right size

(B) molecules of the appropriate shape

(C) the right molecular organization

(D) the proper molecular forces

7. According to the passage, the task of synthesizing a molecular crystal can be compared to

(A) designing a building

(B) building a house

(C) making materials

(D) constructing a lattice