What is the density of a nucleus of mass number $A$?

Q. A nucleus ( mass no. 238 ) initially at rest into another nucleus ( mass no 234 ) emitting an $\alpha$ particle (mass no-4) with the speed of$1.17\times {10}^7$m/sec. Find the recoil speed of the remaining nucleus.

Q. Order of magnitude of density of Uranium nucleus :

(1)10^20 kg/m^3
(2)10^17 kg/m^3
(3)10^14 kg/m^3
(4)10^11 kg /m^3

Q. A nucleus (mass no. $238$) initially at rest decay into another nucleus (mass no. $234$) emitting an $\alpha$ particle (mass no. $4$) with the speed of $1.17\times {10}^{7}m/sec$. Find the recoil speed of the remaining nucleus.