Which of the following relations is not correct ?

Options

A. `1 A.U = 1.496xx 10^(11)m`
B. `1ly = 9.46xx10^(15)m`
C. `1parsec = 3.084xx10^(16)m`
D. `1 ly = 6.3xx10^(-4) A.U.

Answer

To determine which of the given relations is not correct, we need to evaluate each statement one by one.

### Step 1: Analyze the first relation
**Relation 1:** 1 Astronomical Unit (AU) = 1.496 × 10^11 meters

This relation is correct. The astronomical unit is defined as the average distance from the Earth to the Sun, which is approximately 1.496 × 10^11 meters.

### Step 2: Analyze the second relation
**Relation 2:** 1 Light Year (LY) = 9.46 × 10^15 meters

This relation is also correct. A light year is the distance that light travels in one year, and it is approximately equal to 9.46 × 10^15 meters.

### Step 3: Analyze the third relation
**Relation 3:** 1 Parsec = 3.084 × 10^16 meters

This relation is correct as well. A parsec is a unit of distance used in astronomy, and it is approximately equal to 3.084 × 10^16 meters.

### Step 4: Analyze the fourth relation
**Relation 4:** 1 Light Year = 6.3 × 10^(-4) Astronomical Units

To check this relation, we need to convert light years to astronomical units.

1 Light Year = 9.46 × 10^15 meters
1 AU = 1.496 × 10^11 meters

Now, we can convert light years to astronomical units:
\[ \text{1 Light Year in AU} = \frac{9.46 \times 10^{15} \text{ meters}}{1.496 \times 10^{11} \text{ meters/AU}} \]
Calculating this gives:
\[ \text{1 Light Year in AU} \approx 63241.1 \text{ AU} \]

Thus, the relation 1 Light Year = 6.3 × 10^(-4) AU is incorrect.

### Conclusion
The relation that is not correct is:
**1 Light Year = 6.3 × 10^(-4) Astronomical Units.**