[amp_mcq option1=”16 m” option2=”20 m” option3=”24 m” option4=”30 m” correct=”option3″]
The correct answer is $\boxed{\text{B) 20 m}}$.
The detention time is the amount of time that water spends in a tank. It is calculated by dividing the volume of the tank by the flow rate. In this case, the detention time is 2 minutes, or 120 seconds.
The velocity of flow is the speed at which water moves through a pipe or channel. It is calculated by dividing the distance traveled by the time it takes to travel that distance. In this case, the velocity of flow is 0.2 m/s.
The length of the tank is the distance from one end of the tank to the other. It is calculated by multiplying the velocity of flow by the detention time. In this case, the length of the tank is 20 m.
Here is a brief explanation of each option:
- Option A: 16 m. This is the length of a tank with a velocity of flow of 0.2 m/s and a detention time of 1 minute. However, the detention time in this case is 2 minutes, so this option is incorrect.
- Option B: 20 m. This is the correct answer. The length of the tank is calculated by multiplying the velocity of flow by the detention time. In this case, the velocity of flow is 0.2 m/s and the detention time is 2 minutes, so the length of the tank is 20 m.
- Option C: 24 m. This is the length of a tank with a velocity of flow of 0.2 m/s and a detention time of 2.5 minutes. However, the detention time in this case is 2 minutes, so this option is incorrect.
- Option D: 30 m. This is the length of a tank with a velocity of flow of 0.3 m/s and a detention time of 2 minutes. However, the velocity of flow in this case is 0.2 m/s, so this option is incorrect.