The transition from the state $n = 4$ to $n = 3$ in a hydrogen-like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition:

Six identical conducting rods are joined as shown in the figure. Points $A$ and $D$ are maintained at temperatures $200\,^{\circ}C$ and $20\,^{\circ}C$,respectively. The temperature of junction $B$ will be ......... $^{\circ}C$.

Which of the following compounds gives oxygen on fast heating?
$(I)$ $AgNO_3$
$(II)$ $CaCO_3$
$(III)$ $Pb(NO_3)_2$
$(IV)$ $Na_2CO_3$

Why are modern techniques implemented in fisheries?

If $\overrightarrow{a}+\overrightarrow{b}+\overrightarrow{c}=\overrightarrow{0}$ and $|\overrightarrow{a}|=3, |\overrightarrow{b}|=4$ and $|\overrightarrow{c}|=\sqrt{37}$,then the angle between $\overrightarrow{a}$ and $\overrightarrow{b}$ is:

Which of the following is $NOT$ a characteristic of chemisorption?