I believe the answer is D
        
             
        
        
        
Answer:
A) IV: number of hours DV: score
Explanation:
Coz,
IV- is the variable that u change 
DV- is the variable that u test or measure
In this case, we need to change the hours of studying to see how studying for different hours [1 hr, 2hr, etc (( Independant variable coz we're changing the no. of hours)) ] is going to affect the student's score, and in the end, we are measuring the score of each student [this is the dependant variable]. 
 
        
             
        
        
        
1) Chemical reaction
CH3 CH2 OH + O2 ---> CH3COOH + H2O
It is balanced
2) Molar ratios
1 mol CH3 CH2OH : 1 mol O2 : 1 mol CH3COOH : 1 mol H2O
3) Conversion of 7.6 grams of ethanol to moles
Molar mass of CH3CH2OH = 2 * 12g/mol + 6 * 1 g/mol + 16 g/mol = 46 g/mol
moles = mass / molar mass = 7.6 g / 46g/mol = 0.165 mol
4) Use of proportions with the molar ratios:
1mol CH3CH2OH / 1mol O2 = 0.165 mol CH3CH2OH / x => x = 0.165 mol CH3CH2OH.
5)  Conversion of 0.165 mol O2 to grams
mass in grams = number of moles * molar mass = 0.165 mol * (2 * 16g/mol)
mass = 5.28 g ≈ 5.3 g
Answer: 5.3 g
        
                    
             
        
        
        
Answer:
1.5 moles of CO₂ are produced
Explanation:
Based on the chemical equation:
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O<em> -The reaction of the question is wrong-</em>
5 moles of oxygen reacts per mole of propane, C₃H₈, to produce 3 moles of CO₂ and 4 moles of water.
If 2.5 moles of oxygen react and, 5 moles of oxygen produce 3 moles of CO₂, moles of CO₂ produced are:
2.5 moles O₂ * (3 moles CO₂ / 5 moles O₂) = 
<h3>1.5 moles of CO₂ are produced</h3>