Meaning: 'Strongly' means with great intensity or force, indicating that the electrons are held tightly by the nucleus's pull.

Wrong options:

• least: 'Least' implies the lowest degree, which contradicts the idea of attraction to the nucleus.
• weakly: 'Weakly' suggests a low level of attraction, which is incorrect as it does not accurately describe the relationship between electrons and the nucleus.
• unexpectedly: 'Unexpectedly' indicates surprise, which does not fit the scientific context of attraction.

Correct answer: condition

Explanation: The word 'condition' is appropriate as it refers to a necessary state or situation for the movement of electrons, fitting well within the scientific context of the sentence.

Meaning: 'Condition' means a specific requirement or situation that must be met for something to occur, in this case, the movement of electrons.

Wrong options:

• superstition: 'Superstition' refers to a belief not based on scientific evidence, which does not relate to the context of electron movement.
• judgement: 'Judgement' implies a decision or opinion, which is not relevant to the scientific requirement for electron flow.
• presumption: 'Presumption' suggests an assumption made without proof, which does not accurately describe the necessary state for electron movement.

Correct answer: normal

Explanation: The word 'normal' fits grammatically and contextually as it describes a typical state of an atom where balance exists between positive and negative charges, which is essential for understanding atomic structure.

Meaning: 'Normal' means usual or typical, indicating that the atom is in a standard state of charge balance.

Wrong options:

• varied: 'Varied' suggests diversity or difference, which does not apply to the standard state of an atom being balanced.
• strange: 'Strange' implies something unusual or out of the ordinary, which contradicts the concept of a balanced atom.
• singular: 'Singular' refers to something unique or one-of-a-kind, which does not accurately describe the typical state of an atom.

Correct answer: material

Explanation: The word 'material' is suitable as it encompasses any substance that can conduct electricity, fitting the context of the sentence regarding conductors.

Meaning: 'Material' refers to a substance or matter from which things are made, in this case, substances that allow electron flow.

Wrong options:

• metal: 'Metal' is a specific type of material, but the term 'material' is broader and more inclusive in this context.
• molecule: 'Molecule' refers to a group of atoms bonded together, which does not directly relate to the concept of conducting electricity as a whole.
• chemical: 'Chemical' refers to substances with distinct properties, but it does not specifically denote the ability to conduct electricity like 'material' does.

Correct answer: overlap

Explanation: The word 'overlap' fits grammatically and contextually as it describes the interaction of electron orbits, indicating that they share space, which is essential for effective conduction.

Meaning: 'Overlap' means to extend over and cover a part of something, in this case, referring to the electron orbits sharing space to facilitate conduction.

Wrong options:

• collapse: 'Collapse' implies a falling down or failure, which does not fit the context of electron orbits working together.
• diverge: 'Diverge' means to move apart, which contradicts the idea of electron orbits needing to come together for effective conduction.
• appear: 'Appear' suggests visibility or emergence, which does not accurately describe the interaction of electron orbits.