Consider the following statements: 1. A flute of smaller length produces waves of lower frequency. 2. Sound travels in rocks in the form of longitudinal elastic waves only. Which of the statements given above is/are correct?

Statement 1 is incorrect: for wind instruments like the flute the resonant frequency increases as the effective length of the air column decreases — e.g., for an open pipe the fundamental wavelength is λ1 = 2L and f = v/2L, so a shorter flute yields a higher pitch (higher frequency) [2]. Statement 2 is also incorrect: seismic/elastic disturbances in rocks propagate as both primary (P) compressional/longitudinal waves and secondary (S) shear/transverse waves; rocks therefore support longitudinal and transverse elastic waves, not only longitudinal ones [4]. Hence neither statement is correct, so option 4 is the right choice.

Sources

1. [1] https://www.phys.unsw.edu.au/jw/flutes.v.clarinets.html
2. [2] http://labman.phys.utk.edu/phys221core/modules/m12/Standing%20sound%20waves.html
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > Primary Waves (P-Waves) > p. 60
4. [4] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 4: Earths Interior > Secondary Waves (S-Waves) > p. 62