The correct option is **D. displace one another from solutions of their salts**. ### Detailed Explanation: Chlorine, bromine, and iodine are all halogens, which are found in Group 17 of the periodic table. They share several chemical properties due to their similar electronic configurations, which influence their reactivity and interactions with other elements and compounds. 1. **Displacement Reactions**: - Halogens can displace one another in reactions with their salts. This is due to their relative reactivity, which decreases down the group. Chlorine is the most reactive, followed by bromine, and then iodine. - For example, if you have a solution of potassium bromide (KBr) and you add chlorine gas (Cl₂), the chlorine will displace the bromine because it is more reactive: \[ \text{Cl}_2 + 2 \text{KBr} \rightarrow 2 \text{KCl} + \text{Br}_2 \] - Similarly, if you have potassium iodide (KI) and add bromine, bromine will displace iodine: \[ \text{Br}_2 + 2 \text{KI} \rightarrow 2 \text{KBr} + \text{I}_2 \] - This property of displacement is a hallmark of halogen chemistry and is the reason why option D is correct. ### Why the Other Options are Incorrect: **A. dissolve in alkalis**: - While halogens can react with alkalis, they do not simply "dissolve" in them. For example, chlorine reacts with sodium hydroxide (NaOH) to form sodium hypochlorite (NaClO) and sodium chloride (NaCl), but this is a chemical reaction, not a simple dissolution. Bromine and iodine also react with alkalis, but the nature of these reactions varies and does not apply uniformly to all three halogens. Therefore, this option is misleading. **B. react violently with hydrogen without heating**: - This statement is not accurate for all three halogens. Chlorine can react with hydrogen to form hydrogen chloride (HCl) gas, but this reaction typically requires some activation energy (like light or heat) to initiate. Bromine and iodine do react with hydrogen, but the reactions are less vigorous and often require heating. Thus, this option is not a characteristic shared by all three halogens. **C. are liquids**: - This option is incorrect because while bromine is a liquid at room temperature, chlorine is a gas, and iodine is a solid. Therefore, they do not all share the same physical state at room temperature, making this option invalid. ### Summary of Key Points: - **Displacement Reactions**: Chlorine, bromine, and iodine can displace one another in reactions with their salts due to their varying reactivities. - **Reactivity Order**: Chlorine > Bromine > Iodine in terms of reactivity. - **Chemical Properties**: The halogens exhibit different behaviors in reactions with alkalis and hydrogen, which do not uniformly apply to all three. - **Physical States**: Chlorine (gas), bromine (liquid), and iodine (solid) do not share the same physical state at room temperature. This understanding of halogens and their properties is crucial for mastering their chemistry and preparing for related exam questions.