CM TB 03.4 Unstable Nuclei and Radioactive Decay

What is the primary cause of radioactive decay in unstable nuclei?

• Excess energy

• Lack of protons

• High temperature

• Low pressure

Answer explanation

The primary cause of radioactive decay in unstable nuclei is excess energy. When a nucleus has more energy than it can stably contain, it will release that energy through decay processes to achieve a more stable state.

Tags

NGSS.HS-PS1-8

Radioactive decay occurs because unstable nuclei have too much ______.

• Mass

• Energy

• Volume

• Temperature

Answer explanation

Radioactive decay occurs because unstable nuclei have too much energy. This excess energy makes the nucleus unstable, leading it to release particles or radiation to reach a more stable state.

Tags

NGSS.HS-PS1-8

What is an element?

• A mixture of substances

• A pure substance that cannot be broken down into simpler substances by physical or chemical means

• A compound of two or more elements

• A solution of different substances.

Answer explanation

An element is defined as a pure substance that cannot be broken down into simpler substances by physical or chemical means, distinguishing it from mixtures and compounds.

Alpha, beta, and gamma radiation can be characterized in terms of ______.

• color and texture

• mass and charge

• temperature and pressure

• speed and direction

Answer explanation

Alpha, beta, and gamma radiation are types of ionizing radiation characterized by their mass and charge. Alpha particles have a positive charge and mass, beta particles have a negative charge and negligible mass, while gamma rays are neutral and massless.

Tags

NGSS.HS-PS1-8

What is the process by which unstable atoms emit radiation to gain stability?

• Nuclear fusion

• Radioactive decay

• Chemical reaction

• Photosynthesis

Answer explanation

The process by which unstable atoms emit radiation to gain stability is called radioactive decay. This occurs as atoms release energy in the form of radiation, transforming into more stable forms.

Tags

NGSS.HS-PS1-8

Fill in the blank: _______ is the emission of particles or energy from an unstable nucleus.

• Radiation

• Photosynthesis

• Evaporation

• Condensation

Answer explanation

Radiation is the correct answer as it refers to the emission of particles or energy from an unstable nucleus, unlike the other options which pertain to different processes in nature.

Tags

NGSS.HS-PS1-8

What is the process called when substances spontaneously emit radiation?

• Fission

• Fusion

• Radioactivity

• Ionization

Answer explanation

The process when substances spontaneously emit radiation is called radioactivity. This occurs when unstable atomic nuclei release energy in the form of radiation, distinguishing it from fission and fusion, which involve nuclear reactions.

Tags

NGSS.HS-PS1-8

In the late 1890s, scientists noticed some substances spontaneously emitted radiation, a process they called ____.

• Fission

• Fusion

• Radioactivity

• Ionization

Answer explanation

In the late 1890s, scientists discovered that certain substances emitted radiation without external influence, a phenomenon they termed 'radioactivity'. This term specifically describes the spontaneous emission of radiation.

Tags

NGSS.HS-PS1-8

What are the rays and particles emitted called?

• Radiation

• Reflection

• Refraction

• Reaction

Answer explanation

The rays and particles emitted from a source are collectively referred to as radiation. This term encompasses various forms of energy release, distinguishing it from reflection, refraction, and reaction.

Tags

NGSS.HS-ESS1-1

NGSS.HS-PS4-3

A reaction that involves a change in an atom's nucleus is called a ________ reaction.

• Chemical

• Nuclear

• Physical

• Biological

Answer explanation

A reaction that involves a change in an atom's nucleus is called a nuclear reaction. This distinguishes it from chemical, physical, and biological reactions, which do not involve changes to the nucleus.

Tags

NGSS.HS-PS1-8