Answer:
A. O, S, Se
Explanation:
If you look up Oxygen (O), Sulfur (S) and Selenium (Se) in the periodic table, you will see that these three fall under the same column. In the periodic table, elements are arranged in rows and columns. Columns are called groups. The elements that fall under the same group share similar chemical properties.
The elements given above are all in Group VIA or group 16.
Answer:
cần 162,5
Explanation:
100gKNO3 cần 1 mol kno3 từ đó suy ra cần 0,5 mol hg(no3)2 suy ra cần 162,5g hg(no3)2
Answer:
5.72 g ( 1 mol / 180.16 g ) ( 6.022 x 10^23 molecules / mole ) = 1.90x10^23 molecules
