If you have 8 g of a radioactive element there will be Of the radioactive element left after one half life

4g of the radioactive element present

Explanation:

Radioactive elements are atoms that are unstable in normal conditions and are converted in another different atoms.

1 half life express the time that is need to decay the half of the initial amount of the radioactive element.

If initially we have 8g of the radioactive element, after 1 life we will have 8g/2 =

4g of the radioactive element present

Explanation:

We are given a number of particles and asked to convert to moles.

1 mole of any substance contains the same number of particles (atoms, molecules, formula units) : 6.022 *10²³ or Avogadro's Number. For this question, the particles are not specified.

So, we know that 1 mole of this substance contains 6.022 *10²³ particles. Let's set up a ratio.

We are converting 2.98*10²³ particles to moles, so we multiply the ratio by that value.

The units of particles cancel.

The original measurement of particles (2.98*10²³) has 3 significant figures, so our answer must have the same.

For the number we found, 3 sig figs is the thousandth place.

The 8 in the ten-thousandth place (0.4948522086) tells us to round the 4 up to a 5 in the thousandth place.

2.98*10²³ particles are equal to approximately 0.495 moles.