Question

the effect of this decay is that
239 94pu→4 2he + 235 92u
the mass number increases
critical mass is achieved
a neutron is converted to a proton
plutonium is converted to uranium

Explanation:

Step1: Analyze the nuclear reaction

In the given reaction \(^{239}_{94}Pu
ightarrow^{4}_{2}He + ^{235}_{92}U\), we observe the change in the elements.

Step2: Check each option

• Option "the mass number increases": Mass number of \(Pu\) is \(239\), and after decay, sum of mass numbers of \(He\) (\(4\)) and \(U\) (\(235\)) is \(4 + 235=239\). So mass number does not increase.
• Option "a neutron is converted to a proton": In alpha decay (which this is, as \(He\) is emitted), a different process occurs (emission of \(^{4}_{2}He\) nucleus).
• Option "critical mass is achieved": There is no indication in the reaction equation about critical mass.
• Option "plutonium is converted to uranium": The reactant is \(Pu\) (\(^{239}_{94}Pu\)) and one of the products is \(U\) (\(^{235}_{92}U\)).

Answer:

plutonium is converted to uranium