Which of these describes a physical change? Choose the correct answer. O Wood logs are burned in a fire. O Coconut oil begins to crystallize after being placed in a freezer. O Milk left out of the refrigerator for a week starts to smell different. O Sodium hydroxide and hydrochloric acid are mixed in water to form a salt​

The illuminance of a surface varies inversely with the square of its distance from the light source. if the illuminance of a surface is 120 lumens per square meter when its distance from a certain light source is 6 meters, by how many meters should the distance of the surface from the source be increased to reduce its illuminance to 30 lumens per square meter?