Answer:
The only true statement is:
- a. <u><em>Alpha particles have a mass number of 4</em></u>
Explanation:
<em>Alpha particles</em> are radiactive particles equivalent to a helium nucleus, so they have two protons and two neutrons.
Hence, alpha particles, α, are represented as:
The superscript 4 to the left of the chemical symbol is the <em>mass number:</em> 2 protons + 2 neutrons = 4
The subscript 2 to the left of the chemical symbol is the atomic number: 2 protons = 2.
Hence, the statement "a. Alpha particles have a mass number of 4" is true.
As for the other statements, you have:
<em>b. Alpha particles have a nulear charge of +1:</em> <u>false</u>
Since, these particles are the nucleous of the helium atom, the nuclear charge equals the number of protons of this atom: +2. Hence, the statement is false.
c. <em>Alpha particle formation is accompanied by the conversion of a proton into a neutron</em> and d. <em>Alpha particle formation is accompanied by the conversion of a neutron into a proton</em>. <u>(both false</u>)
The conversion of a protons into a neutrons and the conversion of a neutron into a proton are product of other kind of radiactive desintegrations.
- The conversion of a proton into a neutron involves the emission of a positron ( particle with same mass as the electron but positive charge) from the nucleus, which is represented as ⁰₊₁β.
- The conversion of a neutron into a proton involves the emssion of an electron from the nucleus, which is the emission of a beta particle represented as ⁰₋₁β.
Therefore, these last two statements are also false.
