Answer:
Electricity, gravity of earth and structure of atom provide evidence.
Explanation:
The investigation of electricity, gravity of earth and structure of atom helps the student to understand that without touching, one object apply force on another object. In electric current, we can see the property of magnetism due to which it attract and repel objects while in gravity of earth, the earth apply gravitational force to attract objects towards itself. in the structure of atom, proton present in the nucleus which attract the electron present in the shells.
Eukaryotes are organisms whose cells have a nucleus enclosed within a nuclear envelope.
Answer:
Water sample showing pink/purple color is an error.
Explanation:
Biuret is a blue color reagent that changes its color to pink/purple whenever it detects protein in a sample. Water don't contain proteins so it should not show pink/purple color instead it should maintain the blue color. Food items generally contain proteins so it show pink/purple color but it showed blue color.
Error might have caused by wrong marking of the samples, test tube marked with Water might contain a mystery food while Mystery food tube might contain water.
