Question

question 4

1. which of the following are pure substances? select all that apply.

□ oxygen
□ water
□ saltwater
□ lemonade
□ gold

Explanation:

Step1: Recall pure substance definition

A pure substance is matter with a fixed composition, either an element (one type of atom) or a compound (fixed ratio of elements).

Step2: Analyze each option

• Oxygen: Element ($O_2$), fixed composition → pure substance.
• Water: Compound ($H_2O$), fixed ratio → pure substance.
• Saltwater: Mixture (water + salt) → not pure.
• Lemonade: Mixture (water + lemon + sugar etc.) → not pure.
• Gold: Element (Au), fixed composition → pure substance.

Answer:

A. oxygen, B. water, E. gold (assuming options are labeled A:oxygen, B:water, C:saltwater, D:lemonade, E:gold)
(If options are unlabeled by text, the correct ones are "oxygen", "water", "gold" from the list.)