What is the relationship between science and engineering?

Engineering is applied Science and technology. Engineers use different kinds of science (chemistry, physics, Biology) and apply them to accomplish something.

Here are some examples.

Chemistry~ Chemists learned that a material's property (such as metal) can be changed by adding different materials. For example melting copper together with tin makes bronze. By adding the tin and copper in different amounts they will get a weaker or stronger bronze. Chemists also learned that bronze is corrosion resistant (resists rusting)

Engineers then use that base knowledge. For example engineers will make pipes or an underwater device from bronze because they know it resists rust. They will pick what kind of bronze they need based on how strong that part needs to be.

Hope that answered your question.