A : The apparent depth of a tank of water decreases if viewed obliquely.
R : Real depth decreases if viewed obliquely.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements, then mark (4).

Answer

To analyze the given assertion and reason, we will follow these steps:

### Step 1: Understand the Assertion
The assertion states that "the apparent depth of a tank of water decreases if viewed obliquely." This means that when we look at a tank of water from an angle (rather than straight down), the depth that we perceive (apparent depth) seems to be less than the actual depth of the water.

### Step 2: Understand the Reason
The reason states that "real depth decreases if viewed obliquely." Here, real depth refers to the actual physical depth of the water in the tank. We need to determine if viewing the tank obliquely actually changes the real depth.

### Step 3: Analyze the Concept of Apparent Depth
When light passes from a denser medium (water) to a rarer medium (air), it bends away from the normal line. This bending of light causes the object (or the bottom of the tank) to appear higher than it actually is when viewed from an angle. This phenomenon is due to refraction.

### Step 4: Draw a Diagram
To visualize this, we can draw a diagram:
- Draw a tank filled with water.
- Mark the real depth (hr) of the water.
- Draw rays coming from the bottom of the tank. One ray hits the water surface normally, while another hits at an angle.
- Show how the rays bend as they exit the water into the air.

### Step 5: Conclusion on the Assertion
From our analysis, we can conclude that the assertion is true: the apparent depth decreases when viewed obliquely due to the refraction of light.

### Step 6: Conclusion on the Reason
Now, regarding the reason: the real depth of the water does not change regardless of how we view it. The real depth remains constant, but the perceived (apparent) depth changes due to the bending of light.

### Final Conclusion
Thus, we can conclude:
- The assertion is true.
- The reason is false.

The final answer is: Assertion (A) is true, and Reason (R) is false.

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