The answer is temperature (may be wrong)
Answer:
The elements are arranged in seven horizontal rows, called periods or series, and 18 vertical columns, called groups.
Explanation:
Because the amount of hydrogens all depends on the valence electrons
Answer: It will take 3 days for half of a 10 g sample to decay.
Explanation:
Half-life of sample of an isotope X = 3 days
Sample decayed =
N=, time = t
t = 3 days
It will take 3 days for half of a 10 g sample to decay.
When your substance either; change color, start to smell, explode, form bubbles, precipitate, and/or get hotter or colder.