`S_(1)` : Bohr model is applicable for `Be^(2+)` ion .
`S_(2)` : Total energy coming out of any light source is integral multiple of energy of one photon.
`S_(3)` : Number of waves present in unit length if wave number .
`S_(4)` : e/m ratio in cathode ray experiment is independent of the nature of the gas .
Select the correct set of True-False for above statement.

Options

A. `F F T T`
B. `T T F F`
C. `F T T T`
D. `T F F F`

Answer

To solve the question, we will analyze each statement one by one to determine if they are true or false.

### Step 1: Analyze Statement S1
**Statement S1**: Bohr model is applicable for `Be^(2+)` ion.

- The Bohr model is primarily applicable to hydrogen-like atoms, which are atoms with only one electron. The `Be^(2+)` ion has only one electron, making it a hydrogen-like ion. Therefore, the Bohr model can be applied to `Be^(2+)`.

**Conclusion for S1**: True

### Step 2: Analyze Statement S2
**Statement S2**: Total energy coming out of any light source is an integral multiple of energy of one photon.

- The energy of a photon is given by the equation \( E = h \nu \), where \( h \) is Planck's constant and \( \nu \) is the frequency of the photon. The total energy emitted by a light source can indeed be expressed as an integral multiple of the energy of a single photon, as light can be emitted in discrete packets (photons).

**Conclusion for S2**: True

### Step 3: Analyze Statement S3
**Statement S3**: Number of waves present in unit length is called wave number.

- The wave number \( \tilde{\nu} \) is defined as the number of wavelengths per unit distance, typically expressed in reciprocal meters (m⁻¹). Thus, the statement correctly defines wave number.

**Conclusion for S3**: True

### Step 4: Analyze Statement S4
**Statement S4**: e/m ratio in cathode ray experiment is independent of the nature of the gas.

- In the cathode ray experiment, the e/m ratio (charge-to-mass ratio) of electrons is determined by the properties of the electrons themselves, not the gas through which they travel. Therefore, this statement is true.

**Conclusion for S4**: True

### Final Summary of Statements
- S1: True
- S2: True
- S3: True
- S4: True

### Correct Set of True-False
The correct set of True-False for the statements is **TTTT**.

### Answer
The correct option is **TTTT**, which corresponds to option **C**.

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