Questions in nuclei

Select	Question
	Three $\alpha -$ particles and one $\beta -$ particle decaying takes place in series from an isotope $_{88}R{a^{238}}$. Finally the isotope obtained will be
	Half life of a radioactive substance is T. The time taken for all the nuclei to disintegrate will be
	The half life of polonium is 140 days. After how many days, 16 gm polonium will be reduced to 1 gm (or 15g will decay)
	An archaeologist analyses the wood in a prehistoric structure and finds that ${C^{14}}$(Half life = 5700 years) to ${C^{12}}$is only one- fourth of that found in the cells buried plants. The age of the wood is about
	The correct order of ionizing capacity of $a,\;\gamma$and $\gamma - $rays is
	A radioactive element emits 200 particles per second. After three hours 25 particles per second are emitted. The half life period of element will be
	The decay constant of a radioactive element is 0.01 per second. Its half life period is
	Consider a radioactive material of half-life 1.0 minute. If one of the nuclei decays now, the next one will decay
	The half life of the isotope $_{11}N{a^{24}}$is 15 hrs. How much time does it take for $\frac{7}{8}th$ of a sample of this isotope to decay
	If the half life of a radioactive sample is 10 hours, its mean life is