For the electrochemical cell, `(M)|M^(+))||(X^(-)|X)`.
`E^(@)(M^(+)//M)=0.44V` and `E^(@)(X//X^(-))=0.33V`.
From this data one can deduce that

Options

A. ` M + X to M^ ( + ) + X^ ( -) ` is the sponthaneous reaction
B. `M^(+)+X^(-)to M+X` is the spontaneous reaction
C. `E_("cell")=0.77V`
D. `E_("cell)=-0.77V`

Explanation

To solve the problem, we need to analyze the electrochemical cell given by the notation `(M)|M^(+))||(X^(-)|X)`. We are provided with the standard reduction potentials for the half-reactions involving M and X.

### Step-by-Step Solution:

1. **Identify the half-reactions and their standard reduction potentials:**
- For the half-reaction \( M^{+} + e^{-} \rightarrow M \), the standard reduction potential \( E^{\circ}(M^{+}/M) = 0.44 \, V \).
- For the half-reaction \( X^{-} + e^{-} \rightarrow X \), the standard reduction potential \( E^{\circ}(X/X^{-}) = 0.33 \, V \).

2. **Determine the oxidation and reduction processes:**
- In the electrochemical cell, oxidation occurs at the anode and reduction occurs at the cathode.
- Since \( M^{+} \) has a higher reduction potential than \( X^{-} \), \( M \) will be oxidized to \( M^{+} \) (anode), and \( X^{-} \) will be reduced to \( X \) (cathode).

3. **Write the overall cell reaction:**
- The overall cell reaction can be written as:
\[ M + X^{-} \rightarrow M^{+} + X \]

4. **Calculate the standard cell potential \( E^{\circ}_{cell} \):**
- The standard cell potential is calculated using the formula:
\[ E^{\circ}_{cell} = E^{\circ}_{cathode} - E^{\circ}_{anode} \]
- Here, \( E^{\circ}_{cathode} = E^{\circ}(X/X^{-}) = 0.33 \, V \) and \( E^{\circ}_{anode} = E^{\circ}(M^{+}/M) = 0.44 \, V \).
- Plugging in the values:
\[ E^{\circ}_{cell} = 0.33 \, V - 0.44 \, V = -0.11 \, V \]

5. **Interpret the result:**
- Since \( E^{\circ}_{cell} \) is negative, the reaction is non-spontaneous under standard conditions.

### Conclusion:
From the analysis, we can deduce that the correct option is **B**, as it describes the spontaneous reaction correctly based on the calculated cell potential.