In which of the following decay, the element does not change
$\beta$- decay
$\alpha$- decay
$\gamma$- decay
None of these
${ }_{92}^{238} U$ atom disintegrates to ${ }_{84}^{214} Po$ with a half of $45 \times 10^9$ years by emitting $\operatorname{six} \alpha-$ particles and $n$ electrons. Here, $n$ is
The radioactive decay of uranium into thorium is expressed by the equation $_{92}^{238}U \to _{90}^{234}Th + X,$ where $'X'$ is
Alpha particles are
If $_{92}{U^{238}}$ undergoes successively $8 \alpha$- decays and $6 \beta$- decays, then resulting nucleus is
Some laws/processes are given in Column $I$. Match these with the physical phenomena given in Column $II$ and indicate your answer by darkening appropriate bubbles in the $4 \times 4$ matrix given in the $ORS$.
Column $I$ | Column $II$ |
$(A)$ Transition between two atomic energy levels | $(p)$ Characteristic $X$-rays |
$(B)$ Electron emission from a material | $(q)$ Photoelectric effect |
$(C)$ Mosley's law | $(r)$ Hydrogen spectrum |
$(D)$ Change of photon energy into kinetic energy of electrons | $(s)$ $\beta$-decay |