Which of the following is NOT true about compounds?
A) compounds join in specific ratios according to their masses
B) the mass ratio of a specific compound is always the same
C) compounds are random combinations of elements
D) different mass ratio mean different compounds
C is not true.
To determine which of the given options is NOT true about compounds, let's analyze each statement:
A) Compounds join in specific ratios according to their masses: This statement is true. Compounds are formed through chemical reactions where elements combine in specific ratios determined by their atomic masses.
B) The mass ratio of a specific compound is always the same: This statement is also true. The mass ratio of elements in a compound is constant because compounds have fixed formulas that establish the ratio of atoms present.
C) Compounds are random combinations of elements: This statement is NOT true. Compounds are not random combinations of elements; they have a specific arrangement of atoms based on their chemical formulas.
D) Different mass ratios mean different compounds: This statement is true. Different compounds will have different mass ratios because they have different amounts and types of atoms, resulting in different chemical formulas.
Therefore, the correct answer is option C) compounds are random combinations of elements, as this statement is NOT true about compounds.