The ashes left after the woods burns have less mass than the wood had . which statement explains what happened to the rest of the wood's mass.

a. it was lost as heat
b. it is in gases in the air
c. it is still in the wood
d it is in the ashes, but its energy can not be measured as mass.

I believe it is "a" however I could be wrong.

To determine which statement explains what happened to the rest of the wood's mass, we need to understand the process of wood burning. When wood burns, it undergoes a chemical reaction known as combustion. During combustion, the wood combines with oxygen from the air, resulting in the release of energy in the form of heat and light, as well as the formation of ash and gases.

Option a: "It was lost as heat" is a correct explanation. When wood burns, a significant portion of its mass is converted into heat energy, which is released into the surroundings. This heat energy cannot be measured as mass.

Option b: "It is in gases in the air" is also a correct explanation. Some of the wood's mass is converted into gases, such as carbon dioxide, water vapor, and other combustion byproducts. These gases are released into the air during the burning process.

Option c: "It is still in the wood" is incorrect. During combustion, the wood undergoes a chemical change, and its mass is transformed into other forms (such as ash, gases, and heat). The remaining mass of the wood is significantly reduced.

Option d: "It is in the ashes, but its energy cannot be measured as mass" is also incorrect. While a portion of the wood's mass does end up as ash (solid remnants of the wood), the majority of the wood's mass is lost as heat and gases, not contained in the ashes.

Therefore, the most accurate statement explaining what happened to the rest of the wood's mass is option a: "It was lost as heat."