Grade 7...physics Revision...1st Term

Which of these statements was missing from Dalton’s atomic theory?

• Atoms are made up of smaller particles.

• All atoms of the same element are identical.

• Atoms of different elements have different masses.

• Compounds form when atoms of different elements combine in a specific ratio.

Which results support the claim that the atom has a dense, positively charged core? Choose the two statements that apply.

• Some positive particles deflected at sharp angles.

• Some negative particles deflected at sharp angles.

• Most of the positive particles passed straight through the foil.

• Some positive particles bounced back in the direction they came from.

Which incorrect idea in Bohr’s understanding of the atom was replaced by later theories?

• Atoms cannot be divided.

• An atom is mostly empty space.

•       In an atom, electrons orbit the nucleus like planets orbit the sun.

•     An atom includes electrons embedded in a sphere of positive charge.

What is the main difference between the cloud model of the atom and the modern model?

• Only the modern model includes protons.

• The cloud model does not include neutrons.

• Electrons move in specific orbits in the modern model.

• Electrons exist in a cloud around the nucleus in the cloud model.

carbon atom has 6 protons, how many electrons in carbon-14?

• 6

• 8

• 14

• 4

carbon atom has 6 protons, how many neutrons in carbon-14?

• 6

• 8

• 14

• 4

the charge of proton is....................

• positive

• negative

• no charge

the charge of nucleus of atom is......................

• positive

• negative

• no charge

the charge of neutron is ...................

• positive

• negative

• no charge

the charge of electron is......................

• positive

• negative

• no charge