FINAL REVIEW

A sample of iodine-131 has an initial mass of 40.0 g. After 16 days, only 1.25 g of iodine-131 remain. What is the half-life of iodine-131?

• 3 days

• 4 days

• 8 days

• 16 days

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NGSS.HS-PS1-8

Half of a sample of cobalt-60 decays after 2.5 years to form an atom of another element. Half of a sample of iodine-131 decays after 8.1 days to form atoms of another element. Which best explains this difference?

• Iodine-131 has a smaller atomic number than cobalt-60.

• Iodine-131 has a smaller radioactive energy on cobalt-60.

• Iodine-131 has a smaller atomic mass than cobalt-60.

• Iodine-131 has a shorter half-life than cobalt-60.

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NGSS.HS-PS1-8

The process of spontaneous radioactive decay of atoms of unstable elements is best described by which statement?

• A more massive particle absorbs energy and turns into a less massive particle.

• A more massive particle forms one or more less massive particles and emits energy.

• A less massive particle forms one or more massive particles and emits energy.

• A less massive particle absorbs energy and turns into a more massive particle.

Tags

NGSS.HS-PS1-8

An alpha particle that is emitted as nuclear radiation has the same structure as a

• hydrogen nucleus.

• helium nucleus.

• neutron.

• electron.

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NGSS.HS-PS1-8

When an atomic nucleus emits an alpha particle, what happens to the atomic number of the atom?

• Increases by one

• Increases by two

• Decreases by one

• Decreases by two

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NGSS.HS-PS1-8

What type of radiation has the shortest range?

• alpha

• beta

• gamma

• x-ray

Which choice best describes radioactive decay?

• An atom gains an electron as the atom releases energy.

• An atom loses an electron as the atom absorbs energy.

• An atomic nucleus gains mass as the nucleus absorbs energy.

• An atomic nucleus loses mass as the nucleus releases energy.

Tags

NGSS.HS-PS1-8

Which type of radiation has the least penetrating power?

• gamma

• beta

• alpha

• x-ray

How did the quantum mechanical model modify the earlier model of the atom proposed by Niels Bohr?

• The quantum mechanical model claims that the nucleus contained neutrons as well as protons.

• The quantum mechanical model described the orbital radius of electrons as fixed for a given orbital.

• The quantum mechanical model described the position of electrons as variable within a given orbital.

• The quantum mechanical model demonstrated that the mass of an atom was concentrated in its nucleus.

How is Rutherford’s nuclear atom model different from Thomson’s plum pudding model?

• Rutherford’s model describes an atom as a mostly empty space with a dense, positive center, while Thomson’s model describes an atom as a positive sphere embedded with electrons.

• Rutherford’s model describes an atom as a positive sphere embedded with electrons, while Thomson’s model describes an atom as mostly empty space with a dense, positive center.

• Rutherford’s model describes an atom as a solid, positively charged center surrounded by electrons in a cloud, while Thomson’s model describes an atom as a solid sphere.

• Rutherford’s model describes an atom as a solid, positive charge center surrounded by electrons in a cloud, while Thomson’s model describes an atom as a solid sphere.