Question

choose the best answers.
2.1) _____ what is an atom?
a. the smallest piece that makes up matter
b. a type of molecule made up of two or more elements
c. a grain of sand
d. a unit of measurement
2.2) _____ who first proposed the concept of atoms?
a. john dalton
b. democritus
c. aristotle
d. isaac newton

Explanation:

• For 2.1: An atom is defined as the smallest piece that makes up matter. A molecule (option B) is made of atoms. A grain of sand (option C) is a macroscopic object with many atoms. A unit of measurement (option D) is unrelated.
• For 2.2: Democritus first proposed the concept of atoms. John Dalton (option A) had an atomic theory but not the first to propose atoms. Aristotle (option C) opposed the atomic concept. Isaac Newton (option D) was in physics (laws of motion, etc.) not atomic concept origin.

Answer:

2.1) A. the smallest piece that makes up matter
2.2) B. Democritus