Energy is not carried by which of the following waves?

Stationary waves of frequency $300\, Hz$ are formed in a medium in which the velocity of sound is $1200\, m/s$. The distance between a node and the neighbouring antinode is ... $m$.

Two sinusoidal waves with same wavelengths and amplitudes travel in opposite directions along a string with a speed $10 \, ms^{-1}$. If the minimum time interval between two instants when the string is flat is $0.5 \, s$,the wavelength of the waves is .... $m$

$A$ standing wave having $3$ nodes and $2$ antinodes is formed between two atoms having a distance of $1.21 \; \mathring{A}$ between them. The wavelength of the standing wave is .... $\mathring{A}$

The equation of a stationary wave is $Y = 10 \sin \left( \frac{\pi x}{4} \right) \cos (20 \pi t)$. The distance between two consecutive nodes in metres is

Two travelling waves produce a standing wave represented by the equation,
${y} = 1.0 \, \text{mm} \cos(1.57 \, \text{cm}^{-1} x) \sin(78.5 \, \text{s}^{-1} t)$
The node closest to the origin in the region ${x} > 0$ will be at ${x} = \dots \, \text{cm}$.