Reactant are those that combine or reacts to give products !!
so in combustion of ethane ; ethane and o2 are reactants so ... your answer is B !!
Answer: All of these I’m pretty sure
Explanation: It just makes sense
Answer: The volume of 0.235 M
needed to titrate 40.0 mL of 0.0500 M
is 8.51 ml
Explanation:
To calculate the volume of acid, we use the equation given by neutralization reaction:

where,
are the n-factor, molarity and volume of acid which is 
are the n-factor, molarity and volume of base which is 
We are given:

Putting values in above equation, we get:

Thus volume of 0.235 M
needed to titrate 40.0 mL of 0.0500 M
is 8.51 ml