(3) if 8.6 x 1023 molecules of calcium hydroxide are present, what will be its weight in gram ?
(a) 25.8 grams
(b) 74.2 grams
(c) 51.6 grams
(d) 105.9 grams*
molar mass ca (oh) 2 * = 74.096 g\mol
بعدين نحلها بطريقة المقص
74.096_______ 6.022 × 10^23 atoms
× _______ 8.6 × 10^23 atoms
نضرب طرفين في وسطين وحيطلع الناتج 105.9 grams
(6) the number of atoms in the molecule cr2(so4)3 is
(a) 5
(b) 8
(c) 15
(d) 17*