Which of the following orbitals has zero probability of finding the electron in the $YZ$ plane?

When the temperature of a black body increases,it is observed that the wavelength corresponding to maximum energy changes from $0.26 \mu m$ to $0.13 \mu m$. The ratio of the emissive powers of the body at the respective temperatures is

The pattern of standing waves formed on a stretched string at two instants of time (extreme and mean positions) is shown in the figure. The velocity of the two waves superimposing to form stationary waves is $360 \ m/s$ and their frequency is $256 \ Hz$. Which of the following is not a possible value of $t$ (in $sec$)?

The rate constant of a first order reaction at $27^{\circ} C$ is $10^{-3} \ min^{-1}$. The temperature coefficient of this reaction is $2$. What is the rate constant (in $min^{-1}$) at $17^{\circ} C$ for this reaction?

Le Chatelier's principle is not applicable to

Which of the following complex ions is not expected to absorb visible light?