Grade 8 Summative Test EXEMPLAR 1-8

Who introduced the idea that matter is made up of tiny, indivisible particles called atoms?

• Aristotle

• Chadwick

• Democritus

• Lavoisier

Which of the following statements correctly depicts the law of definite proportions?

• The mass ratio of H and O in water (H2O) differs depending on its source.

• The mass ratio of C and O in CO2 from burning fossil fuel and CO2 from human and animal respiration is different.

• The mass of oxygen in water is always 8 times that of hydrogen present regardless of where it came from.

• The mass of carbon in carbon dioxide is always 3 times that of oxygen present regardless of where it came from.

Which of the following pairs of compounds can be used to illustrate the law of multiple proportions?

• ZnS2 and ZnCl2

• NH4 and NH4Br

• HBr and H2O2

• CO and CO2

Who is the scientist who discovered the law of definite proportions?

• Proust

• Lavoisier

• Dalton

• J.J. Thomson

Whose work showed for the first time that atoms emit negatively charged particles?

• John Dalton

• Ernest Rutherford

• J.J. Thomson

• Robert Millikan

Which experimental evidence did Thomson use to prove that particles made up cathode rays rather than light?

• Cathode rays refract through a prism.

• Cathode rays are emitted in a vacuum tube.

• Cathode rays produce interference patterns.

• Cathode rays are deflected in the presence of electric and magnetic fields.

What model shows an atom as a ball of positive charge with electrons embedded in it, much like chocolate chips spread through cookie dough?

• Chocolate Chip model

• Plum and nuts model

• Plum Pudding model

• Chocolate Pudding model

Which of the following statements did NOT correctly describe the results of the experiments done to determine the nature of the atom?

• The cathode ray tube proved that electrons are negatively charged particles.

• Rutherford’s thin gold foil experiment led to the discovery of the charge of the nucleus.

• The results of Rutherford’s experiment supported J.J. Thomson’s plum pudding model.

• Millikan’s oil drop experiment showed that the charge of the electron is -1.6022 x 10-19 C

If Rutherford’s experiment proved the correctness of J.J. Thomson’s model, what would he observe?

• alpha particles are greatly deflected by the foil.

• alpha particles bounced back from the foil.

• Alpha particles had little to no deflection.

• more alpha particles are formed.

Who is the scientist whose experiment led to the idea that the center of the atom is a dense positive charge?

• John Dalton

• Ernest Rutherford

• J.J. Thomson

• Robert Millikan