Analyze the Fission Reaction:
The nuclear fission of \(^ {235}_{92} \text{U}\) typically occurs when it absorbs a neutron, forming \(^ {236}_{92} \text{U}\) in an excited state, which then undergoes fission.
The reaction can be written as:
\[ ^{235}_{92} \text{U} + ^{1}_{0} \text{n} \rightarrow \text{fission fragments} + \text{neutrons} \]
Check for Conservation of Mass Number and Atomic Number:
For each option, verify that the total mass number (A) and atomic number (Z) on the right side of the reaction matches the total on the left side.
Total Mass Number (A): \(235 + 1 = 236\)
Total Atomic Number (Z): \(92\)
Evaluate Each Option:
Option 1: \(^{144}_{56} \text{Ba} + ^{89}_{36} \text{Kr} + 4 ^{1}_{0} \text{n}\)
Mass number: \(144 + 89 + 4 \times 1 = 236\)
Atomic number: \(56 + 36 + 4 \times 0 = 92\)
This satisfies the mass and atomic number balance.
Option 2: \(^{140}_{56} \text{Xe} + ^{94}_{38} \text{Sr} + 3 ^{1}_{0} \text{n}\)
Mass number: \(140 + 94 + 3 \times 1 = 237\)
Atomic number: \(56 + 38 + 3 \times 0 = 94\)
This does not satisfy the balance.
Option 3: \(^{153}_{51} \text{Sb} + ^{99}_{41} \text{Nb} + 3 ^{1}_{0} \text{n}\)
Mass number: \(153 + 99 + 3 \times 1 = 256\)
Atomic number: \(51 + 41 + 3 \times 0 = 92\)
This does not satisfy the balance.
Option 4: \(^{144}_{56} \text{Ba} + ^{89}_{36} \text{Kr} + 3 ^{1}_{0} \text{n}\)
Mass number: \(144 + 89 + 3 \times 1 = 236\)
Atomic number: \(56 + 36 + 3 \times 0 = 92\)
This satisfies the mass and atomic number balance.
Conclusion:
Only Option 4 satisfies the conservation of both mass number and atomic number in the nuclear fission process.
A small bob A of mass m is attached to a massless rigid rod of length 1 m pivoted at point P and kept at an angle of 60° with vertical. At 1 m below P, bob B is kept on a smooth surface. If bob B just manages to complete the circular path of radius R after being hit elastically by A, then radius R is_______ m :
In the following \(p\text{–}V\) diagram, the equation of state along the curved path is given by \[ (V-2)^2 = 4ap, \] where \(a\) is a constant. The total work done in the closed path is: 
Let \( ABC \) be a triangle. Consider four points \( p_1, p_2, p_3, p_4 \) on the side \( AB \), five points \( p_5, p_6, p_7, p_8, p_9 \) on the side \( BC \), and four points \( p_{10}, p_{11}, p_{12}, p_{13} \) on the side \( AC \). None of these points is a vertex of the triangle \( ABC \). Then the total number of pentagons that can be formed by taking all the vertices from the points \( p_1, p_2, \ldots, p_{13} \) is ___________.
Consider the following two reactions A and B: 
The numerical value of [molar mass of $x$ + molar mass of $y$] is ___.