Minimum number of reactants a chemical equation can have is 2.
We don't know that at all. The 3rd law says that the REaction is opposite and EQUAL to the action. We don't know where that "twice as much" comes from.
Answer: 26.84 m/s
Explanation:
Given
Original frequency of the horn 
Apparent frequency 
Speed of sound is 
Doppler frequency is
Where,
Insert values
![\Rightarrow 246=228\left[\dfrac{340+v_o}{340-0}\right]\\\\\Rightarrow 366.84=340+v_o\\\Rightarrow v_o=26.8\ m/s](https://tex.z-dn.net/?f=%5CRightarrow%20246%3D228%5Cleft%5B%5Cdfrac%7B340%2Bv_o%7D%7B340-0%7D%5Cright%5D%5C%5C%5C%5C%5CRightarrow%20366.84%3D340%2Bv_o%5C%5C%5CRightarrow%20v_o%3D26.8%5C%20m%2Fs)
Thus, the speed of the car is 
The total heat that is needed by the water to get converted to steam is calculated below through the equation,
H = (Hv)(n)
where H is the heat, Hv is the heat of vaporization (40.67 kJ/mol), and n is the number of mols. Substituting the known values,
H = (40.66 kJ/mol)(1.5 mol) = 60.99 kJ
Calculating for the time,
t = (60990 J) / (24 J/s)
t = 2541.25 s
Answer: 2541.25 s or approximately 42.35 minutes
