The half-life of lead-212 is 11h. How much of a 100-g sample of lead-212 is left after 33h? Someone please help

After 33 hours, the sample would have undergone a halving 3 times, as its half life is 11 hours.

This would mean that after 33h, only 12.5grams of Lead-212 are left over.

If a hydrogen atom is neutral, it must also have  one electron. an oxygen atom (o) has an atomic number of eight (8). this means a neutral oxygen atom has eight protons and eight electrons. the element actium (ac) has an atomic number of 89, so it has 89 protons and 89 electrons in a neutral atom