Assertion : Radioactive nuclei emit ⁻ particles. Reason : Electrons exist inside the nucleus.

Step-by-step solution

Nuclear stability depends upon the ratio of neutron to proton. If the n / p ratio is more than the critical value, then a neutron gets converted into a proton forming a ⁻ particle in the process. n p+e⁻ The ⁻ particle ( .e⁻ ) is emitted from the nucleus in some radioactive transformation. So electrons do not exist in the nucleus but they result in some nuclear transformation.