For the reaction
`CH_3-CH_2-CH(Cl) CH_3 underset(475K)overset(KOH(alc))(to)`
`C_2H_5-CH=CH_2(A) +CH_3-CH=CH-CH_3(B)`

Options

A. A' Predominates
B. B' Predominates
C. Both A and B are formed in equal molar ratio
D. The product ratio depends upon the temperature

Explanation

To solve the given reaction and determine the major and minor products, we will follow these steps:

### Step 1: Identify the Reactant
The reactant is given as CH₃-CH₂-CH(Cl)-CH₃. This can be expanded to show its structure more clearly:
- The structure is:
```
CH₃
|
CH₃-CH-CH₂
|
Cl
```

### Step 2: Understand the Reaction Conditions
The reaction is treated with alcoholic KOH at a temperature of 475 K. Alcoholic KOH is a strong base that promotes elimination reactions (specifically E2 mechanism) leading to the formation of alkenes by removing a halogen (Cl in this case) and a hydrogen atom from adjacent carbon atoms.

### Step 3: Identify Possible Elimination Sites
In the structure, we have two possible sites for elimination:
1. Removing a hydrogen from the carbon adjacent to the carbon bearing the chlorine (C-3).
2. Removing a hydrogen from the carbon at the end of the chain (C-2).

### Step 4: Determine the Products
- **Product A**: If we remove a hydrogen from C-3 and the Cl from C-4, we form:
```
CH₃
|
CH₃-CH=CH₂ (Product A)
```
- **Product B**: If we remove a hydrogen from C-2 and the Cl from C-3, we form:
```
CH₃
|
CH₂=CH-CH₃ (Product B)
```

### Step 5: Apply Zaitsev's Rule
According to Zaitsev's rule, the more substituted alkene is favored as the major product.
- **Product A** has a double bond between C-2 and C-3, with one substituent on C-2 (CH₃).
- **Product B** has a double bond between C-3 and C-4, with two substituents on C-3 (CH₃ and CH₂).

Since Product B is more substituted (it has more alkyl groups attached to the double bond), it will be the major product.

### Step 6: Conclusion
Based on Zaitsev's rule, Product B predominates over Product A. Therefore, the answer to the question is that Product B will dominate.

### Final Answer
**B predominates.**

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