This problem is very easy to answer. You simply have to look at the subscripts of each element of the compound.
1. For caffeine, which has a molecular formula of C₈H₁₀N₄O₂, it contains 8 atoms of Carbon, 10 atoms of Hydrogen, 4 atoms of Nitrogen and 2 atoms of Oxygen.
2. For Iron(III) Sulfate, which has a molecular formula of Fe₂(SO₄)₃, it contains 2 atoms of Iron, 3 atoms of Sulfur, and 12 atoms of Oxygen.
        
             
        
        
        
Answer:
Mg(NO4)2 is 180.3 g/mol
Explanation:
First find the substance formula. 
Magnesium Nitrate.
Magnesium is a +2 charge.
Nitrate is a -1 charge. 
So to balance the chemical formula,
We need 1 magnesium atom for every nitrate atom. 
2(1) + 1(-2) = 0
So the substance formula is Mg(NO4)2. 
Now find the molar mass of Mg(NO4)2. 
Mg = 24.3 amu
N = 14.0 amu
O = 16.0 amu
They are three nitrogen and twelve oxygen atoms. 
So you do this: 24.3 + 14.0(2) + 16.0(8) = 180.3 g/mol
So the molar is mass is 180.3 g/mol. 
The final answer is Mg(NO4)2 is 180.3 g/mol
Hope it helped!
 
        
             
        
        
        
Answer:
empirical formula is C7H3NCl2
Explanation:
too much work too explain and im lazy
 
        
             
        
        
        
<h3>
Answer:</h3>
0.89 J/g°C
<h3>
Explanation:</h3>
Concept tested: Quantity of heat 
We are given;
- Mass of the aluminium sample is 120 g 
- Quantity of heat absorbed by aluminium sample is 9612 g
- Change in temperature, ΔT = 115°C - 25°C
                                                       = 90°C
We are required to calculate the specific heat capacity;
- We need to know that the quantity of heat absorbed is calculated by the product of mass, specific heat capacity and change in temperature.
That is;
Q = m × c × ΔT
- Therefore, rearranging the formula we can calculate the specific heat capacity of Aluminium.
Specific heat capacity, c = Q ÷ mΔT
                                          = 9612 J ÷ (120 g × 90°C)
                                          = 0.89 J/g°C
Therefore, the specific heat capacity of Aluminium is  0.89 J/g°C
 
        
        
        
Chlorine is the correct answer so A