$${}_{92}^{235}$$U, nucleus absorbs a neutron and distintegrate in $${}_{54}^{139}$$Xe, $${}_{38}^{94}$$Sr and $$x$$ so, what will be product $$x$$?

A human body required 0.01 m activity of radioactive substance after 24 hours. Half life of radioactive substance is 6 hours. Then inhection of maximum activity of radioactive substance that can be injected is

If a $${}_b^aX$$ species emits first a position, then two a and two b particles and in the last, one a, is also emitted and gets converts to $${}_d^c$$Y species. So correct relation is

A 300 grams radioactive sample at initial half life is 3 hours. After 18 hours remaining quantity