Which statement is always true when nuclear fusion occurs

Question

Responses:

The combined number of protons and neutrons remains constant.

The number of protons in the resulting nucleus is less than in each starting nucleus.

The total number of protons and neutrons in each nucleus remains constant.

The number of protons in the resulting nucleus is double that of a starting nucleus.

Answer 1

The statement that is always true when nuclear fusion occurs is:

The combined number of protons and neutrons remains constant.

In nuclear fusion, lighter atomic nuclei combine to form a heavier nucleus, and while this process can release energy, the total number of nucleons (protons and neutrons) in the reacting nuclei is conserved.

Answer 2

Use the equation to answer the question.

21H+ 21H→ 42H+energy

Which statement best describes the mass numbers of the atoms in the reaction?
Responses:

There are two atoms with the mass number 1

There is one atom with a mass number of 2.

There are two atoms with mass numbers of 2.

There is one atom with a mass number of 1.

Answer 3

In the reaction \( ^2_1\text{H} + ^2_1\text{H} \rightarrow ^4_2\text{H} + \text{energy} \), the notation \( ^2_1\text{H} \) represents deuterium, which has a mass number of 2.

Analyzing the options based on the given reaction:

• There are two atoms with the mass number 1: This is incorrect because both starting atoms are deuterium, each with a mass number of 2.
• There is one atom with a mass number of 2: This is incorrect because there are two atoms with mass number 2 involved in the reaction.
• There are two atoms with mass numbers of 2: This is correct because the two \( ^2_1\text{H} \) atoms have mass numbers of 2.
• There is one atom with a mass number of 1: This is incorrect; all relevant atoms in this equation have mass numbers of 2 or 4.

Thus, the best statement is:

There are two atoms with mass numbers of 2.

Answer 4

Why would pushing the south pole of two magnets together provide a good model for the fusion of two hydrogen nuclei?
Responses:

Some nuclei repel each other, and some attract each other, just like magnets.

The positive charges of the nuclei make it difficult for the nuclei to fuse, just like the repulsion of the two magnets.

If the nuclei fused, it would destroy both of them, just like the two magnets would be destroyed.

Only negative nuclei can fuse with positive nuclei, just like the north and south poles of magnets.

Answer 5

The best response that explains why pushing the south poles of two magnets together provides a good model for the fusion of two hydrogen nuclei is:

The positive charges of the nuclei make it difficult for the nuclei to fuse, just like the repulsion of the two magnets.

In the case of hydrogen nuclei (which are positively charged due to their protons), there is a repulsive electrostatic force between them when they approach each other, similar to how two like poles of magnets (south-south) repel each other. Overcoming this repulsion is necessary for fusion to occur, which typically requires very high temperatures and pressures to allow the nuclei to get close enough together to fuse.

Answer 6

How is the mass number calculated for an atom involved in nuclear fusion?
Responses:

It is the number of neutrons.

It is the number of protons plus electrons.

It is the number of protons plus neutrons.

It is the number of electrons.

Answer 7

The correct response for how the mass number is calculated for an atom involved in nuclear fusion is:

It is the number of protons plus neutrons.

The mass number of an atom is the total count of protons and neutrons in its nucleus, and electrons do not contribute to the mass number, as they have negligible mass compared to protons and neutrons.

Answer 8

Which change will always take place in nuclear fusion?
Responses:

A nucleus with a smaller mass than any of the reactants will be produced.

The total charge will be greater than before the fusion took place.

A nucleus with a greater mass than any of the reactants will be produced.

The total charge will be less than before the fusion took place.

Answer 9

The correct response regarding what change will always take place in nuclear fusion is:

A nucleus with a smaller mass than any of the reactants will be produced.

In nuclear fusion, when two light nuclei combine to form a heavier nucleus, the resulting nucleus often has a mass that is slightly less than the sum of the masses of the original nuclei. This mass difference is converted into energy according to Einstein's equation \( E=mc^2 \). Thus, it can be said that a nucleus with a smaller mass (and potentially also smaller total mass number) than the sum of the reactants is produced, which implies the release of energy.