The half-life of the radioactive element unobtanium dash 53 is 20 seconds. if 32 grams of unobtanium dash 53 are initially present, how many grams are present after 20 seconds? 40 seconds? 60 seconds? 80 seconds? 100 seconds?

when the half-life is the amount of time which the radioactive isotopes need to

be in half.

So when w start with 32 g of unobtanium 53 so:

1 - after 20 sec the number of grams remain = 32/2

= 16 g

2 - and after 40 sec the number of grams remain

16 g will cut in half:

= 16 / 2

= 8 g

3 - and after 60 sec the number of grams remain

8 g will cut in half:

= 8g / 2

= 4 g

4 - and after 80 sec the number of grams remain

4 g will cut in half:

= 4 g / 2

= 2 g

5-after 100 sec the number of grams remain

2 g will cut in half:

= 2g / 2

= 0 g

after 100 sec there are no grams remain