Answer:
four elements
Explanation:
He = 1s²
Be = 1s² 2s²
C = 1s² 2s² 2p²
Mg = 1s² 2s² 2p⁶ 3s²
Si = 1s² 2s² 2p⁶ 3s² 3p²
Ca = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
Valence electrons are those electrons which are present in outer most electronic shell.
He, Be, Mg, Ca these four elements have 2 valence electrons.
While Si and C have four valance electrons.
Answer:
Cu(OH)2 + 2HCl → CuCl2 + 2H2O
Answer:
0.50 g Caffeine
Explanation:
Step 1: Given data
Concentration of caffeine by weight in tea leaves: 5.0%
Mass of tea leaves: 10. g
Step 2: Calculate the maximum weight of caffeine that can be isolated
The concentration of caffeine by weight in tea leaves is 5.0%, that is, there are 5.0 g of caffeine per 100 g of tea leaves. The maximum weight of caffeine in 10. g of tea leaves is:
10. g Tea leaves × 5.0 g Caffeine/100 g Tea leaves = 0.50 g Caffeine
