During the change of $O_2$ to $O_2^-$ ion,the electron adds to which one of the following orbitals?

The incorrect stability order of $+3$ and $+1$ states of $13^{th}$ group elements (boron family) is

In a series $LCR$ circuit,$R=300 \Omega, L=0.9 \text{ H}, C=2.0 \mu\text{F}$ and $\omega=1000 \text{ rad/s}$,then the impedance of the circuit is: (in $\Omega$)

$A$ light wave of wavelength $\lambda$ is incident on a slit of width $d$. The resulting diffraction pattern is observed on a screen at a distance $D$. If the linear width of the principal maximum is equal to the width of the slit,then the distance $D$ is:

Which one of the following halogens liberates oxygen,when passed through hot concentrated $KOH$ solution?

$A$ system is provided with $50 \ J$ of heat and the work done on the system is $10 \ J$. What is the change in internal energy of the system in joules?