Question

1. according to daltons atomic theory, which statement is true?

all matter is made of atoms.
atoms of the same element are different.
physical reactions occur when atoms join, separate, or rearrange.
atoms sometimes chemically combine in whole number ratios.

Explanation:

• Option 1: Dalton's atomic theory states that all matter is composed of atoms. This is a fundamental postulate of his theory.
• Option 2: Dalton's theory says atoms of the same element are identical in mass and properties. So, the statement "Atoms of the same element are different" is false.
• Option 3: Chemical reactions (not physical reactions) occur when atoms join, separate, or rearrange according to Dalton's theory.
• Option 4: Atoms chemically combine in simple whole - number ratios in compounds (not sometimes).

Answer:

All matter is made of atoms.