The percent composition of each element can be calculated as follows:
% composition = (mass of element / total mass) * 100
The total mass of the quarter is given to be 5.670 grams
Mass of Cu = 5.198 grams
Mass of Ni = 0.472 grams
Substitute in the above equation to get the mass percentage of each element as follows:
% of Cu = (5.198/5.670) * 100 = 91.675%
% of Ni = (0.472/5.670) * 100 = 8.325%
Answer:

Explanation:
Alkaline earth metals are in group 2. The number of valence electrons of elements in group 2 is 2.
Answer:
3.37 × 10²³ molecules
Explanation:
Given data:
Mass of C₆H₁₂O₆ = 100 g
Number of molecules = ?
Solution:
Number of moles of C₆H₁₂O₆:
Number of moles = mass/molar mass
Number of moles = 100 g/ 180.16 g/mol
Number of moles = 0.56 mol
Number of molecules:
1 mole contain 6.022 × 10²³ molecules
0.56 mol × 6.022 × 10²³ molecules /1 mol
3.37 × 10²³ molecules