Alkenes on reaction with meta-chloroperoxybenzoic acid (MCPBA ) produces epoxides. When styrene is reacted with mCPBA it gives 2-phenyloxirane as shown below,
 
        
        
        
Relative formula mass C₅H₁₁ = 71
Now divide the molar mass by the RFM = 142.32 / 71 = 2
Now C₍₅ₓ₂₎H₍₁₁ₓ₂) = C₁₀H₂₂
Hope that helps
        
             
        
        
        
The statement which describes how NO2- reacts in this equilibrium:
<span>H2SO3(aq) + NO2-(aq) HSO3-(aq) + HNO2(aq
is the second option - </span><span>B. as a Brønsted-Lowry base by accepting a proton.
</span>This is because bases take proton H+ in order to become HNO2. 
        
                    
             
        
        
        
D. <span>carbon and hydrogen</span>