Question

1. table sugar, or sucrose, is made of carbon, hydrogen, and oxygen atoms. in nature, carbon is often a black solid, and hydrogen and oxygen are colorless gases. why does sugar look different from the elements from which it is made?

a. elements are always gases. molecules are always solids.
b. light reacts differently to molecules than it does to elements.
c. the properties of molecules are different from the elements they are made from.
d. the properties of molecules are highly similar to the elements they are made from.

1. what happens to the atoms in a chemical reaction?

a. they are destroyed.
b. they are rearranged.
c. they turn into energy.
d. they change into atoms of different elements.

1. juan is reading the information that came with new medicine he has to take. one of the ingredients is lactose (c₁₂h₂₂o₁₁). what can juan conclude about lactose based on the formula?

a. some people may be allergic to lactose.
b. lactose is a key ingredient in many medicines.
c. a lactose molecule contains 12 atoms of carbon.
d. a lactose molecule contains 45 atoms of carbon.

1. salt and sugar appear similar, but their crystals look different at the atomic level. what does this say about the molecular structures of salt and sugar?

a. salt and sugar molecules contain the same atoms arranged in different patterns.
b. salt and sugar molecules contain different atoms arranged in different patterns.
c. salt and sugar molecules are made of different atoms arranged in the same pattern.
d. salt and sugar molecules are made of the same atoms arranged in the same patterns.

Explanation:

• Question 6:
• Molecules have different properties from the elements they are made of. Sugar (a molecule) has different properties (like appearance) than carbon (a black solid), hydrogen, and oxygen (colorless gases). Option C is incorrect as molecules' properties are different. Option A is wrong as elements aren't always gases. Option B is not the main reason.
• Question 7:
• In a chemical reaction, atoms are rearranged. According to the law of conservation of mass, atoms are not destroyed (so A is wrong), they don't turn into energy (C is wrong), and they don't change into atoms of different elements (D is wrong).
• Question 8:
• From the formula \(C_{12}H_{22}O_{11}\), we can directly see that a lactose molecule contains 12 atoms of carbon. Option A and B can't be concluded from the formula. Option D is wrong as the number of carbon atoms is 12.
• Question 9:
• Salt (\(NaCl\)) is made of sodium (\(Na\)) and chlorine (\(Cl\)) atoms. Sugar (e.g., sucrose) is made of carbon (\(C\)), hydrogen (\(H\)), and oxygen (\(O\)) atoms. So they have different atoms. Also, since their crystals look different at the atomic level, their atomic arrangements (patterns) are different.

Answer:

• Question 6: C. The properties of molecules are different from the elements they are made from.
• Question 7: B. They are rearranged.
• Question 8: C. A lactose molecule contains 12 atoms of carbon.
• Question 9: B. Salt and sugar molecules contain different atoms arranged in different patterns.