Name the following nuclear reactions :
(a) ` ""_(92)^(235) +_(0)^(1)n to_(38)^(90)Sr + _(54)^(143) Xe + 3_(0)^(1) n + gamma`
(b) ` ""_(1)^(3) H +_(1)^(2) H to_(2)^(4) He + _(0)^(1) n + _(0)^(1) n + gamma`

Answer

To name the given nuclear reactions, we will analyze each reaction step by step.

### Step 1: Analyze Reaction (a)
The first reaction is:
\[ \ _{92}^{235}U + \ _{0}^{1}n \rightarrow \ _{38}^{90}Sr + \ _{54}^{143}Xe + 3 \ _{0}^{1}n + \gamma \]

1. **Identify the reactants**: The reactants are Uranium-235 (U-235) and a neutron (n).
2. **Identify the products**: The products are Strontium-90 (Sr-90), Xenon-143 (Xe-143), three neutrons, and gamma radiation.
3. **Determine the type of reaction**: In this reaction, a neutron collides with a Uranium nucleus, causing it to split into two smaller nuclei (Sr and Xe) and release additional neutrons and gamma radiation.

**Conclusion for Reaction (a)**: This is a **nuclear fission reaction** because a larger nucleus (Uranium-235) splits into smaller nuclei (Strontium and Xenon) along with the release of neutrons and energy.

### Step 2: Analyze Reaction (b)
The second reaction is:
\[ \ _{1}^{3}H + \ _{1}^{2}H \rightarrow \ _{2}^{4}He + \ _{0}^{1}n + \ _{0}^{1}n + \gamma \]

1. **Identify the reactants**: The reactants are Tritium (H-3) and Deuterium (H-2).
2. **Identify the products**: The products are Helium-4 (He-4), two neutrons, and gamma radiation.
3. **Determine the type of reaction**: In this reaction, two hydrogen isotopes combine to form a single helium nucleus and release neutrons and energy.

**Conclusion for Reaction (b)**: This is a **nuclear fusion reaction** because two lighter nuclei (Tritium and Deuterium) combine to form a heavier nucleus (Helium-4) along with the release of energy.

### Final Answers:
(a) Nuclear Fission Reaction
(b) Nuclear Fusion Reaction