Answer:
Mass = 182.4 g
Explanation:
Given data:
Number of moles of Al₂O₃ = 3.80 mol
Mass of oxygen required = ?
Solution:
Chemical equation:
4Al + 3O₂ → 2Al₂O₃
Now we will compare the moles of aluminum oxide and oxygen.
Al₂O₃ : O₂
2 : 3
3.80 : 3/2×3.80 = 5.7
Mass of oxygen:
Mass = number of moles × molar mass
Mass = 5.7 mol × 32 g/mol
Mass = 182.4 g
Answer:

Explanation:
1. Calculate the adult life
If the elephant is an adult from its 10th birthday until the day before its 56th birthday, its
Adult life = 55 - 10 + 1 = 46 yr
2. Convert years to days

3. Convert days to pounds of feed

4. Convert pounds to kilograms and megagrams

Note: The answer can have only two significant figures because that is all you gave for age of the elephant.
Answer:
Manganese
Explanation:
At Mass - No neutrons = Atomic Number = #protons in nucleus
47 - 22 = 25 => At. No. 25 is Manganese (Mn)
Answer:
6.9 (two sig figs)
Explanation:
2.375 + 4.5 = 6.875 = 6.9
When adding or subtracting, sig figs are determined by the least number of digits past the decimal point.
Answer:
The answer is B an open system allows energy and mass to move in and out of it
Hope it helps