To solve the question, we need to evaluate each statement provided and determine which ones are correct.
### Step 1: Analyze Statement A
**Statement A:** "Smack is chemically diacetylmorphine which is a white, odorless, bitter crystalline compound."
- **Analysis:** Smack is indeed a common name for heroin, which is chemically known as diacetylmorphine. It is a white, odorless, bitter crystalline substance. Therefore, this statement is **correct**.
### Step 2: Analyze Statement B
**Statement B:** "Crack is a coca alkaloid, is obtained from coca plant Theobroma cocoa, and is usually snorted."
- **Analysis:** Crack is a form of cocaine, which is a coca alkaloid. However, it is obtained from the plant Erythroxylum coca, not Theobroma cocoa (which is the cocoa plant used for chocolate). The part about it being snorted is correct, but the source plant is incorrect. Therefore, this statement is **incorrect**.
### Step 3: Analyze Statement C
**Statement C:** "Smoking is associated with an increased risk of cancer of the lung."
- **Analysis:** This statement is well-supported by scientific research. Smoking is a major risk factor for lung cancer due to the presence of numerous carcinogens in tobacco smoke. Therefore, this statement is **correct**.
### Step 4: Analyze Statement D
**Statement D:** "The chronic use of drugs and alcohol damages the nervous system and liver."
- **Analysis:** Chronic use of drugs and alcohol is known to cause significant damage to the nervous system and liver. Alcohol abuse can lead to liver cirrhosis and neurological issues. Therefore, this statement is **correct**.
### Conclusion
After analyzing all statements:
- Statement A: Correct
- Statement B: Incorrect
- Statement C: Correct
- Statement D: Correct
Thus, the correct statements are A, C, and D.
### Final Answer
The correct statements are A, C, and D.
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