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 :
Which one of the following graphs accurately represents the plot of partial pressure of CS₂ vs its mole fraction in a mixture of acetone and CS₂ at constant temperature?

Let \( \alpha = \dfrac{-1 + i\sqrt{3}}{2} \) and \( \beta = \dfrac{-1 - i\sqrt{3}}{2} \), where \( i = \sqrt{-1} \). If
\[ (7 - 7\alpha + 9\beta)^{20} + (9 + 7\alpha - 7\beta)^{20} + (-7 + 9\alpha + 7\beta)^{20} + (14 + 7\alpha + 7\beta)^{20} = m^{10}, \] then the value of \( m \) is ___________.