Chlorine

Step 1: Understand the reaction of AgCl with sunlight
Silver chloride (AgCl) is a white solid that undergoes a photochemical reaction when exposed to sunlight. In this reaction, AgCl decomposes into silver (Ag) and chlorine gas (Cl ).
Step 2: Analyze the color change
When Silver Chloride (AgCl) is exposed to sunlight, it breaks down into silver metal (which is grey in color) and chlorine gas. This process is a type of photodecomposition, leading to a color change from white to grey.
Step 3: Conclusion
The correct color change is from white to grey upon exposure to sunlight.

Step 1: Understand what an acid anhydride is
An acid anhydride is an oxide that, when reacted with water, forms an oxyacid. For non-metals like chlorine, this is especially common. Step 2: Identify the oxide and write its hydrolysis reaction
The molecular formula given is Cl₂O₇, which is the heptoxide of chlorine. When it reacts with water: This reaction yields perchloric acid (HClO₄), a strong acid where chlorine is in the +7 oxidation state.
Step 3: Conclusion
Cl₂O₇ is the anhydride of perchloric acid (HClO₄).