Long Test 1.2 - Science (2025-2026)

Schrödinger introduced the quantum mechanical model of the atom. Which of the following everyday scenarios correctly illustrates the concept of electron probability clouds?

• Predicting the exact seat a student will choose in a classroom

• Predicting the most likely spots where students usually sit in class

•  Measuring the exact distance of every chair in the classroom
  

• Counting the total number of chairs in the classroom

 What improvement did Bohr’s model add to Rutherford’s model?

• Electrons are embedded in a sphere of positive charge.

• Electrons orbit the nucleus in fixed energy levels.

• Electrons cannot exist in regions of probability

• Electrons make up most of the atom’s mass.

Rutherford’s model could not explain why negatively charged electrons do not collapse into the positively charged nucleus. Which later model addressed this weakness?

• Dalton’s Atomic Theory

• Thomson’s Plum Pudding Model

• Bohr’s Planetary Model

• Schrödinger’s Quantum Mechanical Model

Which of the following sequences correctly arranges the historical development of atomic models from earliest to most recent?

• Billiard ball → Plum Pudding → Nuclear → Planetary→ Quantum Mechanical

• Plum Pudding→ Nuclear→Billiard ball → Planetary → Quantum Mechanical

• Nuclear→Billiard ball → Planetary→ Plum pudding → Quantum Mechanical

• Billiard ball → Nuclear → Plum Pudding → Planetary→ Quantum Mechanical

Dalton claimed atoms of the same element are identical in mass. Why is this incorrect based on modern discoveries?

• Atoms can change into different elements in chemical reactions.

• Isotopes of the same element have different masses.

• Atoms can be divided into protons and neutrons.

• Atoms of one element are identical to atoms of another.

According to the Quantum Mechanical Model, which statement about electrons is most accurate?

• Electrons move in fixed circular orbits at constant speeds.

• Electrons exist in regions of high probability called orbitals.

• Electrons are embedded inside a positively charged sphere.

• Electrons orbit the nucleus like planets around the sun.

What limitation of Dalton’s model is corrected by Thomson’s model?

• Atoms can form compounds by combining.

• Atoms contain subatomic particles like electrons.

• Atoms are indivisible and indestructible.

• Atoms of different elements have different properties.

According to the student, “Protons and electrons are always equal in number”. Is this claim correct? 

• Incorrect, neutrons balance protons.

• Incorrect, they cannot exist together.

• Correct, they are always balanced.

• Correct only for neutral atoms; ions differ.

Which statement is TRUE about a negative ion or an atom with a negative charge? The number of electrons is….

• equal to the number of protons

• greater than number of protons

• less than number of protons

• five and the number of protons is zero

A neutral atom of chlorine (Cl) has an atomic number of 17 and a mass number of 35.  How many subatomic particles does it contain?

• 17 protons, 17 electrons, 18 neutrons

• 18 protons, 18 electrons, 17 neutrons

• 17 protons, 18 electrons, 17 neutrons

• 17 protons, 17 electrons, 35 neutrons