plz help

Yes. alpha decay and beta decay can occur in the same molecule ie., the same element can emit the radiations but they are one after the other till the element attains stability.

Alpha-decay occurs in very heavy elements, like Uranium. If their nucleus has too many protons (i.e. it is proton-rich), it is unstable. Such a nucleus can become more stable by emitting an alpha particle.

Alpha decay leaves a daughter nucleus that is of a different element to the parent one. When a nucleus emits an alpha-particle:

atomic mass decreases by 4.
atomic number decreases by 2
e.g. Americium-241 (an α-source used in smoke detectors), which has an atomic number of 95 and an atomic mass of 241, will decay to Neptunium-237 (which has an atomic number of 93 and an atomic mass of 237).

The equation would look like this:

241 Am
→
237 Np + α

95 93
Now an alpha particle is the same as the nucleus of a Helium atom (2 protons and 2 neutrons). So it helps to balance equations if we write He instead of α as follows:

241 Am
→
237 Np + 4 He

95 93 2

Alpha decay leaves a daughter nucleus that is of a different element to the parent one. When a nucleus emits an alpha-particle:

atomic mass decreases by 4.
atomic number decreases by 2
e.g. Americium-241 (an α-source used in smoke detectors), which has an atomic number of 95 and an atomic mass of 241, will decay to Neptunium-237 (which has an atomic number of 93 and an atomic mass of 237).

The equation would look like this:

241 Am
→
237 Np + α

95 93
Now an alpha particle is the same as the nucleus of a Helium atom (2 protons and 2 neutrons). So it helps to balance equations if we write He instead of α as follows:

241 Am
→
237 Np + 4 He

95 93 2

Beta decay occurs in nuclei, such as Strontium-90, that are unstable because they have too many neutrons in their nuclei (i.e. they are very neutron-rich). They become more stable by emitting a beta particle.

Beta decay also leaves a daughter nucleus that is of a different element to the parent one.

A beta particle is just an electron. What is an electron doing coming out of a nucleus? Under certain conditions, a neutron can decay, turning into a proton plus an electron. The proton remains in the nucleus, whilst the electron (the beta particle) flies off at high speed.

This means that when a nucleus emits a beta-particle:

atomic mass is unchanged
atomic number increases by 1
e.g. Strontium-90 undergoes beta decay and forms Yttrium-90

90 Sr
→
90 Y + β-

38 39
Because a beta particle is just an electron, we could write e instead of β in the equation as follows:

90 Sr
→
90 Y + 0 e

38 39 -1