Which of the following radioactive isotopes is used in the detection of thyroid cancer?

In a meter bridge,the null point is found at a distance of $25\, cm$ from $A$. If now a resistance of $10\,\Omega$ is connected in parallel with $S$,the null point occurs at the midpoint of $AB$. The value of $R$ is .............. $\Omega$. (in $.67$)

$A$ speaker emits a sound wave of frequency $f_0$. When it moves towards a stationary observer with speed $u$,the observer measures a frequency $f_1$. If the speaker is stationary,and the observer moves towards it with speed $u$,the measured frequency is $f_2$. Then:

On combustion of $Li$,$Na$,and $K$ in excess of air,the major oxides formed,respectively,are:

$A$ fully charged capacitor has a capacitance $C$. It is discharged through a small coil of resistance wire,embedded in a block of specific heat $s$ and mass $m$ under thermally isolated conditions. If the temperature of the block is raised by $\Delta T$,the potential difference $V$ across the capacitor initially is

Chemically,borax is: