Show a numerical setup for calculating the number of moles in the sample of caco3

Ahydrogen atom has 1 electron. how many bonds can hydrogen form? a) 1 b) 2 c) 3 d) 4 e) 5

In chemistry, the type of an atom (what element it is) is determined by: a) the number of protons it contains in its nucleus. b) the number of neutrons it contains in its nucleus. c) the number of protons it has in a cloud around the nucleus. d) the number of neutrons it has in a cloud around the nucleus. e) the number of electrons it exchanges with its neighbors.

How many moles are in 1.26*10^24 particles in significant figures