Question

1. choose the best answer.

which statement is true about oxygen gas, which is made of two elements of oxygen chemically combined (o₂)?
it is a compound.
it is a molecule.
it is a molecule and a compound.

1. choose all that apply.

which two of these are correct examples of physical properties?
combustion
bolling point
malleability
reactivity

Explanation:

1. A compound is made of different elements. Since \(O_2\) is made of only oxygen (same element), it is not a compound. A molecule is a group of atoms bonded together. \(O_2\) is a molecule (two oxygen atoms bonded).
2. Physical properties are characteristics that can be observed without changing the substance's chemical identity. Boiling point (temperature at which a substance changes from liquid to gas) and malleability (ability to be hammered into thin sheets) are physical. Combustion (ability to burn, a chemical change) and reactivity (how a substance reacts chemically) are chemical properties.

Answer:

1. It is a molecule.
2. boiling point, malleability