Length of Resonance Tube:
The length of the resonance tube is given as 150 cm. This length refers to the distance from the opening of the tube to the lowest level of liquid inside it.

Resonance Conditions:
To achieve resonance in a tube, the length of the tube must be an integral multiple of half the wavelength of the sound wave produced. In other words, the length of the tube must satisfy the equation:

L = (n x λ) / 2

Where L is the length of the tube, n is the harmonic number, and λ is the wavelength of the sound wave.

Given Wavelength:
In this case, the given wavelength is 80 cm. We need to find the minimum level of liquid that will produce resonance for this wave.

Solving for the Minimum Level:
To find the minimum level of liquid that produces resonance, we can rearrange the equation for resonance conditions:

L = (n x λ) / 2

Since we want to find the minimum level, n will be the smallest possible value, which is 1.

Plugging in the given values, we have:

150 cm = (1 x 80 cm) / 2

Simplifying the equation, we get:

150 cm = 40 cm / 2

Dividing 40 cm by 2, we find:

150 cm = 20 cm

Therefore, the minimum level of liquid required for resonance with a sound wave of 80 cm wavelength is 20 cm.

Summary:
- The length of the resonance tube is given as 150 cm.
- Resonance occurs when the length of the tube is an integral multiple of half the wavelength of the sound wave.
- The given wavelength is 80 cm.
- By rearranging the resonance condition equation and plugging in the values, we find that the minimum level of liquid required for resonance is 20 cm.

10 cm