**Question:** Toxic substance commonly used by washermen to put marks on clothes: Delhi 06

**Core Concept:** The question is referring to a toxic substance used by washermen in Delhi to mark clothes, specifically mentioning that this substance is commonly used in Delhi. The substance is known as Delhi 06.

**Why the Correct Answer is Right:** Delhi 06 is a reference to a toxic substance called DDT (Dichlorodiphenyltrichloroethane), an organochlorine insecticide. In the context of this question, DDT is used by washermen to mark clothes due to its distinctive color and durability. DDT is lipophilic, which means it easily penetrates fabrics and does not easily wash off, making it suitable for marking clothes.

**Why Each Wrong Option is Incorrect:**

A. **Paraquat:** This is another toxic substance, but it is not lipophilic and is not commonly used by washermen to mark clothes. Paraquat is a highly toxic herbicide and is not suitable for this purpose.

B. **Sodium Thiosulfate:** Sodium thiosulfate is a chemical compound used as a neutralizing agent for poisoning caused by various substances, including certain pesticides. It is not a toxic marking agent for clothes.

C. **Lead Acetate:** Lead acetate is a chemical used in some industries, but it is not a common marking substance for clothes, as it is toxic and not suitable for marking purposes.

D. **Acid Dyes:** Acid dyes are used to color textiles, but they are not toxic and do not have the desired marking properties for washermen.

**Clinical Pearl:** Delhi 06 refers to DDT, a toxic substance with distinct marking properties, making it the correct answer in this context. The use of DDT by washermen for marking clothes is a historical practice, particularly evident during the British reign in India when DDT was used as an insecticide in agriculture, and clothes were sometimes accidentally contaminated. This practice has been phased out due to environmental concerns and the development of safer alternatives.

**Core Concept Explanation:** DDT is an organochlorine insecticide that was widely used globally in the past to control insect populations. Its widespread use led to environmental concerns and restrictions worldwide. In India, DDT was particularly used for agricultural purposes during British colonial rule.

**Why the Correct Answer is Right:** The correct answer, DDT (Delhi 06), is a toxic substance that possesses properties suitable for marking clothes due to its lipophilic nature and durability. Its lipophilic nature allows it to penetrate fabrics, making the mark visible and resistant to washing.

**Why Each Wrong Option is Incorrect:**

A. **Paraquat:** Paraquat is another toxic substance used as a herbicide. However, like DDT, it is not suitable for marking clothes as it is not lipophilic and does not penetrate fabrics effectively.

B. **Toxic Dyes:** Toxic dyes are not suitable for marking clothes as they are not lipophilic and do