What was rutherford's contribution to our knowledge of atoms

He proposed the theory of the structure of atoms
(1)The nucleus at the centre of the atom has the positive charge.Most of the mass of the atom is concentrated in the nucleus.
(2)The negatively charged electrons revolve around the nucleus in specific orbits
(3)In comparison with the size of the atom , the nucleus is very very small.

(d) 15 bouquets

Explanation:

it is given that kate alone can arrange 20 bouquets per day

and it is also given that when Kate and his husband William work together then they arrange 35 bouquets

we have to find the William marginal product

if both together arrange 35 bouquets and Kate alone arrange 20 bouquets it means that 35-20=15 bouquets are arranged by William alone

so the marginal product of William is 35-20=15 so the option will be the correct answer