Problem 14 - A Complete Resource Book in Chemistry for JEE Main

Question

Cadmium rods are used for which purpose? (a) to emit electrons (b) to adsorb neutrons (c) to emit neutrons (d) to absorb electrons

Step-by-Step Solution

Answer

Cadmium rods are used to adsorb neutrons.

Step 1: Understanding the Problem

Read the question carefully. You need to identify the purpose of cadmium rods. Consider each option to see which one fits the typical role of cadmium rods.

Step 1: Focus on Option (a)

Option (a) suggests that cadmium rods are used to emit electrons. Generally, cadmium rods are not used for electron emission.

Step 2: Focus on Option (b)

Option (b) suggests that cadmium rods are used to adsorb neutrons. In nuclear reactors, cadmium rods are utilized as control rods due to their ability to absorb excess neutrons, preventing the reactor from overheating.

Step 3: Focus on Option (c)

Option (c) proposes that cadmium rods emit neutrons. Cadmium is not known to emit neutrons, but rather to absorb them.

Step 4: Focus on Option (d)

Option (d) states that cadmium rods absorb electrons. Historically, cadmium's primary use in reactors is not related to electron interaction.

Step 6: Conclusion

From analyzing all the options, the most appropriate use of cadmium rods is option (b), adsorbing neutrons in nuclear reactors.

Key Concepts

Cadmium Rods

Cadmium rods play a crucial role in nuclear reactors. They are primarily used as control rods because of their excellent neutron absorption capabilities. Cadmium is a unique element with a high likelihood of interacting with neutrons, ultimately capturing them. This property makes cadmium rods very effective in controlling the rate of nuclear reactions. The placement of these rods within the reactor allows them to effectively regulate the number of neutrons present in the reactor core.

• Cadmium rods absorb neutrons, preventing them from further inducing fission reactions.
• By controlling neutron availability, the nuclear reaction speed is moderated, ensuring safe reactor operation.

Cadmium fundamentally manages the energy output of a nuclear reactor, safeguarding against unintentional power surges.

Neutron Absorption

Neutron absorption is a vital process in nuclear reactions. It involves the capture of neutrons by an atomic nucleus. This process is instrumental in regulating the nuclear fission reaction, which is the core of nuclear power generation. The ability to absorb neutrons helps to prevent an uncontrolled chain reaction which could lead to reactor damage or failure.

• Absorbed neutrons are removed from the chain reaction, reducing the overall reaction rate.
• This process helps maintain criticality, where each fission event just sustains future reactions without escalation.

Neutron absorption is a safety measure that keeps the nuclear reactor from overheating by controlling the number of neutrons that participate in fission reactions.

Nuclear Reactor Control Rods

Control rods are essential components of a nuclear reactor, and cadmium rods often serve this role. Their primary function is to manage the fission rate of uranium and plutonium. By inserting more rods into the reactor core, the number of free neutrons—and thereby the fission rate—can be decreased. This is crucial for energy production and for ensuring operational safety.

• Control rods adjust the energy output, stabilizing the reactor's performance.
• By absorbing neutrons, control rods prevent excessive fission reactions, regulating the nuclear reaction pace.

These rods can be moved in and out of the reactor core to modulate nuclear reactions, making them a key factor in nuclear reactor safety and functionality.