During alpha decay of a nucleus, how does the neutron to proton ratio change?

Explanation

Consider an element `""_(83)X^(210)`
In beta decay, `""_(83)X^(210) to ""_(90)X^(234) + ""_(2)He^(4)`
Initial neutrons to proton ratio will be `(238-92)/92 = 146/92`
Neutron to proton ratio after alpha decay will be `(234-90)/90 = 144/90`
Thus, in alpha decay the ratio of neutron to proton ratio will increase.