5.2.3 - 5.2.4 RADIOACTIVITY PHYSICS IGCSE 0625 (PART 2)

Why isotopes tend to be radioactive?

• An excess of neutrons in the nucleus

• An excess of electrons in the nucleus

• The nucleus being too heavy

• •The nucleus being too light

A decay process causes deduction in number of mass number of the parent element.

name the decay process.

• alpha decay

• beta decay

• gamma decay

A decay process causes additional in number of atomic number of the parent element.

name the decay process.

• alpha decay

• beta decay

• gamma decay

name the X.

• Helium nucleus

• electron

• proton

• Hydrogen nucleus

The diagram shows a decay equation. What is the value of A and Z?

• A: 206

  Z: 80

• A: 210

  Z: 81

• A: 210

  Z: 80

• A: 210

  Z: 83

Determine the radioactive rays that are emitted in each stage of the above series of the decay

Why gamma decay do not alter atomic and mass number of the radioisotope?

Because

• gamma ray is an energy

• gamma ray is a nucleon

• gamma ray is a particle

"Time required for mass / activity/ number of nuclei of a radioactive substance to fall to half its initial value."

This is definition of

• radioactivity

• decay process

• half-life

• isotope

A sample of radioactive material stored in the laboratory has an initial activity

of 20 s^-1 . If its half-life is 9 minutes, how much is its activity after 45 minutes?

• 2.5 s^-1

• 1.25 s^-1

• 0.625 s^-1

• 5 s^-1

A radioactive material stored in the laboratory has a half-life of 4 days. Calculate the number of days taken for the activity of a sample of radioactive material to reduce to 6.25% of its initial activity.

• 12 days

• 9 days

• 16 days

• 20 days