Question

1. substance composition

images a and b show two different substances. which of the following statements accurately describe the two substances? (choose two)
a. images a and b are both composed of carbon and oxygen.
b. images a and b are both molecules containing 2 atoms of oxygen.
c. images a and b are both compounds containing only 2 atoms of oxygen.
d. image a is an element and image b is a compound.
e. image a is a compound and image b is an element.

1. physical and chemical changes

a glass of lemonade with ice sits outside on a hot day. the ice begins to melt. which of the following has occurred? (choose two)
a. the ice has melted, which is a chemical change.
b. the ice has melted, which is a physical change.
c. the lemonade has been diluted by the water from the melting ice.
d. the water from the melting ice has been diluted by the lemonade.
e. the water from the melting ice has not diluted the lemonade.

1. chemical formulas and compounds

the chemical formulas of three substances are recorded as c₃h₆o, c₄h₁₀o, and c₅h₁₂o. these compounds contain the same ________ because each formula has the same ______. they are different compounds because they have different ________. which terms complete the sentences best?
a. molecules; chemical formulas; chemical symbols
b. elements; chemical formulas; chemical symbols
c. molecules; chemical symbols; chemical formulas
d. elements; chemical symbols; chemical formulas

1. glucose composition

glucose is a simple sugar with the molecular formula c₆h₁₂o₆. which option correctly identifies the type and number of each atom found in glucose?
a. glucose contains 24 atoms of carbon, 24 atoms of hydrogen, and 24 atoms of oxygen.
b. glucose contains 6 atoms of carbon, 12 atoms of hydrogen, and 6 atoms of oxygen.

Explanation:

1. Substance composition involves distinguishing elements and compounds. Elements consist of one type of atom; compounds have multiple. Common scenarios include elemental molecules (e.g., O₂) and compounds (e.g., CO₂).
2. Ice melting is a physical change (no new substance). Melting ice adds water, diluting the lemonade solution.
3. The formulas share C, H, O (same elements/symbols) but differ in atom counts (different formulas).
4. Glucose's formula C₆H₁₂O₆ directly indicates 6 C, 12 H, 6 O atoms.

Answer:

1. B. Images A and B are both molecules containing 2 atoms of oxygen, D. Image A is an element and image B is a compound.
2. B. The ice has melted, which is a physical change, C. The lemonade has been diluted by the water from the melting ice.
3. D. elements; chemical symbols; chemical formulas
4. B. Glucose contains 6 atoms of carbon, 12 atoms of hydrogen, and 6 atoms of oxygen.