If in the case of a radioisotope the value of half-life $(T_{1/2})$ and decay constant $(\lambda)$ are identical in magnitude, then their value should be

The radium and uranium atoms in a sample of uranium mineral are in the ratio of $1 : 2.8 \times 10^6$. If the half-life period of radium is $1620$ years,the half-life period of uranium will be:

Decay of $_{92}U^{235}$ is $...$ order reaction.

If the disintegration constant is $6.93 \times 10^{-6} \ s^{-1}$,then the half-life of $_{6}C^{14}$ will be:

$A$ freshly prepared radioactive element has a half-life of $2 \ hr$. It emits radiation whose intensity is $64$ times the permissible safe level. The minimum time after which it would be possible to work with this sample is .......... $hr$.

$^{18}_{8}O$ has a half-life of $4650 \text{ years}$. $200 \text{ mg}$ of a sample of $^{18}_{8}O$ is reduced to $25 \text{ mg}$ in ......... $\text{years}$.