During radioactive decay, the element can change?

In the early twentieth century the apparatus shown in the diagram was used to investigate atomic structure. When He²⁺ particles were fired at a thin sheet of gold, most of the particles were detected at point P. What conclusion can be drawn from the detection of He²⁺ particles at point P?

When He²⁺ particles were fired at a thin sheet of gold, about 1 in 8000 of the particles were detected at point Q. What conclusion can be drawn from the detection of He²⁺ particles at point Q?

Which of these correctly shows the numbers of sub-atomic particles in a ⁴¹K⁺ ion?

Which of these correctly shows the numbers of sub-atomic particles in a ²¹Na⁺ ion?

Which of these correctly shows the numbers of sub-atomic particles in a ⁴²Ca²⁺ ion?

Which model of the atom is denoted as the "plum pudding" model?

An atom in which the number of protons is greater than the number of neutrons is:

Which of these atoms has the smallest number of neutrons?

Americium-241 (²⁴¹₉₅Am) is an isotope of americium. Which of the isotopes given in the table below is not an isotope of americium?

The graph shows how the number of americium-241 nuclei in a sample changes with time. How many years does it take for the number of americium-241 nuclei to decrease from 10,000 to 5,000?

A teacher used a Geiger-Muller tube and counter to measure the number of counts in 2 minutes for a radioactive rock. The counter recorded 980 counts in two minutes. The background radiation count rate was 0.25 counts per second. Calculate the count rate for the rock.

A householder is worried about the radiation emitted by the granite worktop in his kitchen. 1 kg of granite has an activity of 1250 Bq. The kitchen worktop has a mass of 180 kg. Calculate the activity of the kitchen worktop in Bq.

In an experiment, a teacher put a 2 mm thick lead sheet in front of a radioactive source. She used a detector and counter to measure the radiation passing through the lead sheet in one minute. She then put different numbers of lead sheets, each 2 mm thick, in front of the radioactive source and measured the radiation passing through in one minute. The readings taken by the teacher are plotted in the graph. How does the amount of radiation transmitted by the lead change as the total thickness of the lead is increased?

An atom that loses an electron is called an _____________________and has an overall _________________________ charge.

Carbon-14 and carbon-12 are two of the isotopes of carbon. The nucleus of a carbon-12 atom has the same number of ________________ as the nucleus of a carbon-14 atom.

State the number of neutrons in an atom of iodine-135 (¹³⁵₅₃I)

The graph shows how the number of americium-241 nuclei in a sample changes with time. What is the half-life of americium-241?

The half-life of As-81 is 33s. How long does it take for a 100g sample of As-81 to decay to 6.25g?

How old is a bone if it presently contains 0.3125g of carbon-14 and it was estimated to originally contain 80g? The half-life of carbon-14 is 5730 years.

Sodium-25 was to be used in an experiment, but it took 3 minutes to get the sodium from the reactor to the laboratory. If 5 mg of sodium-25 was removed from the reactor, how many mg of sodium-25 would be available to use in the laboratory? The half-life of Na-25 is 60 seconds.

Use the graph to determine the half-life of the radioactive sample. The x-axis label is time in seconds

State the likely count rate after 180 seconds

The graph shows how the count rate from a sample of technetium-99 changes with time. State the half-life of technetium-99.

The graph shows how the count rate from a sample of technetium-99 changes with time. What would the count rate be after 24 hours?

he graph shows how the count rate of a sample of iodine-131 changed over 24 days. What is the half-life of iodine-131?

U‐238 has a half‐life of 4.46 billion years. How much U‐238 was present initially if 2 grams remains after 13.38 billion years?