(A): `Ti(IV)` in aqueous solutions is colour less.
(R): `Ti(IV)` has no electrons in d-subshell. 

Options

A. Both A & R are true, R is the correct explanation of A
B. Both A & R are true, R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true

Answer

To solve the assertion and reason question regarding Titanium (IV) in aqueous solutions, we can break down the information step by step.

### Step 1: Understanding the Assertion
The assertion states that Titanium (IV) in aqueous solutions is colorless.

### Step 2: Understanding the Reason
The reason given is that Titanium (IV) has no electrons in the d-subshell.

### Step 3: Analyzing Titanium's Electronic Configuration
Titanium (Ti) has an atomic number of 22. Its electronic configuration is:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d² 4s²

When Titanium loses four electrons to form Ti(IV), the electrons are removed first from the 4s subshell and then from the 3d subshell. The configuration for Ti(IV) becomes:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁰ 4s⁰

### Step 4: Identifying the d-Electron Count
In the Ti(IV) state, there are no electrons in the d-subshell (3d⁰).

### Step 5: Relating Electron Configuration to Color
The color of transition metal ions in solution is often due to the presence of unpaired d-electrons. Since Ti(IV) has no d-electrons, it cannot exhibit any color.

### Conclusion
Both the assertion and reason are true:
- Assertion (A): Ti(IV) in aqueous solutions is colorless.
- Reason (R): Ti(IV) has no electrons in the d-subshell, which explains why it is colorless.

### Final Answer
Both A and R are true, and R is the correct explanation of A.