Which event would be impossible to explain by using john dalton’s model of the atom?
a)an iron atom emits particles when it is struck by light.
b)an oxygen atom combines with two hydrogen atoms to form water.
c)an acid reacts with a base to form salt and water.
d)the atoms in sodium metal react with water.

The scientist thought that the atom was the smallest particle in the universe is John Dalton. He established the atomic theory which consists of five; elements are made of extremely small particles called atoms, atoms of different element have different sizes, mass and physic – chemical properties, atoms cannot be divided further, destroyed or created, atoms can combine to form compounds and in chemical reaction, atoms can be combined, separated or rearranged. 

Adozen is 1221/12 = 1.751.75 x 12 = 21therefore, 1.75 is the answer.