thorium decay chain meaning in Hindi

Examples

1. Alpha particles that produce nucleogenic reactions come from natural alpha particle emitters in uranium and thorium decay chains.
2. The exceptions are elements 87; all four occur in nature, but only in very minor branches of the uranium and thorium decay chains, and thus all save element 87 were first discovered by synthesis in the laboratory rather than in nature ( and even element 87 was discovered from purified samples of its parent, not directly from nature ).