Half-life

Technetium's atomic number is

How many neutrons would Technetium-99 have?

Technetium-99 undergoes beta decay, meaning when it transmutes, it emits

• high-energy electromagnetic radiation

• a proton

• an electron

• a helium nucleus

When Technetium-99 transmutates, its nuclei would turn into

• Technetium-98 nuclei

• Technetium-100 nuclei

• Ruthenium-98 nuclei

• Ruthenium-99 nuclei

Technetium-99 has a half-life of 6 hours. How much of a 0.5g sample of technetium-99 would remain after it has been undergoing radioactive decay for 24 hours? _____ g (rounded to 2 d.p.)

Suppose you leave a 0.2g sample of technetium-99 in a cupboard overnight. Technetium transmutates into ruthenium. How long would the sample of technetium have been left in the cupboard for, if there was 0.175g of ruthenium present the next day? ______ hours

Smoke detectors contain radioactive americium. The americium emits an alpha particle when it transmutates. Alpha particles are

• positively-charged

• negatively-charged

• not charged, because they are pure energy

The americium in smoke detectors decays into neptunium-237. Which isotope of americium is being used here?

• Ar-241

• A-233

• Am-233

• Am-241

If a sample of americium-241 is left to undergo alpha decay, the transmutation is fairly slow. After 1296 years, 87.5% of the americium will be gone. What is the half-life of americium? ________ years