Half-life is the duration needed for a compound to decay into half of its initial weight. In this case, the initial weight is 100gram. The calculation for the final weight should be:
final weight= initial weight * (1/2)^(duration/half-life)
final weight= 100 grams * (1/2)^(20days/5 days)
final weight= 100 grams * (1/2)^(4)
final weight= 100 * 1/16= 100/16 gram= 6.25 grams
Most chemical elements are solid at room temperature. Some elements exist as gases but only two elements, mercury (Hg) and bromine (Br) are liquids at room temperature (approx 25oC). Hope this helped you!
