The reaction between C2H2 and O2 is as follows:
2C2H2 + 5O2 = 4CO2 + 2H2O
After balancing the equation, the reaction ratio between C2H2 and O2 is 2:5.
The moles of O2 in this reaction is 84.0 mol. According to the above ratio, the moles of C2H2 needed to react completely with the O2 is 84.0mole *2/5 = 33.6 mole. 
        
                    
             
        
        
        
Answer:a) 0.1 mole. b) 4g. c) 2% d)  196 mL
Explanation: in 200mL , 0.1mole
mw NaOH = 40g/mol —> 4g in 0.1 mole
4g in 200mL so 2g in 100mL
density NaOH = 1g/mL so if 4g in 200 mL,  4mL , 196 mL water
 
        
             
        
        
        
Answer:
<h2>4.0 </h2>
Explanation:
The pH of a solution can be found by using the formula
![pH = - log [ { H}^{+}]](https://tex.z-dn.net/?f=pH%20%3D%20-%20log%20%5B%20%7B%20H%7D%5E%7B%2B%7D%5D)
From the question we have

We have the final answer as
<h3>4.0</h3>
Hope this helps you