2.
MCaCl2=40+71=111g/mol
1mol CaCl2(111g)......contine 6,022*10²³ {molecule CaCl2}...2*6,022*10²³ioni Cl⁻
xg CaCl2...........................................................6,022*10²³ ioni Cl⁻
X=.....reprezinta masa de substanta pura deci md, mai stii ms=500g deci poti afla c=md*100/ms=........
3. Z=a
A=2a+54 numarul neutronilor este A-Z=.......