The standard reduction electrode potentials of the three electrodes P,Q and R are respectively -1.76V, 0.34V and 0.8V. Then

Options

A. Metal Q will displace the cation of P from its aqueous solution and deposit the metal P
B. Both metals Q and R will displace the cation of P from its aqueous solution and deposit the metal P
C. Metal R will displace the cation of P from its aqueous solution and deposit the metal R
D. Metal P will displae the cation of R from its aqueous solution and deposit the metal R

Explanation

To solve the problem regarding the standard reduction potentials of electrodes P, Q, and R, we will analyze the given potentials and determine which metals can displace each other based on their reduction potentials.

### Step-by-Step Solution:

1. **Identify the Standard Reduction Potentials:**
- Electrode P: \( E^\circ = -1.76 \, \text{V} \)
- Electrode Q: \( E^\circ = 0.34 \, \text{V} \)
- Electrode R: \( E^\circ = 0.80 \, \text{V} \)

2. **Understand the Displacement Reaction:**
- A metal can displace another metal from its salt solution if it has a higher reduction potential. This means that the more positive the reduction potential, the more likely it is to be reduced and thus displace a less noble metal.

3. **Compare the Reduction Potentials:**
- Since \( E^\circ \) for P is the most negative, it is the most reactive and will not be displaced by any of the other metals.
- Q has a higher reduction potential than P but lower than R.
- R has the highest reduction potential among the three.

4. **Determine Displacement Relationships:**
- **Metal Q:** Can displace metal P because \( E^\circ(Q) > E^\circ(P) \).
- **Metal R:** Can displace both metals P and Q because \( E^\circ(R) > E^\circ(Q) \) and \( E^\circ(R) > E^\circ(P) \).
- **Metal P:** Cannot displace either Q or R due to its lower reduction potential.

5. **Conclusion:**
- Metal Q can displace metal P.
- Metal R can displace both metals P and Q.
- Therefore, the correct relationships are:
- Q displaces P.
- R displaces both P and Q.

### Final Answer:
- Metal Q will displace metal P.
- Metal R will displace both metals P and Q.