Answer:

Explanation:
We know that the speed of light is equal to 
We need to find how far the light travel in 3 days.
Speed of an object is equal to distance covered divided by time taken.
Also, 1 day = 86400 s
3 days = 259200 s
So,


So, the light will travel
in 3 days.
D. Adding more of the chemical will heat the water but only up to a certain temperature
<h3>Further explanation</h3>
Chemical changes are changes in the process that produce new substances that are different from the initial/ forming substances. Chemical changes are usually known as chemical reactions. So there are products/reactions and reactants and there is a change in the molecule/particle
The chemical reaction is usually followed by the release of heat, gas, change in color, precipitate substance etc
The heat that occurs in the addition of chemicals is caused by the reaction with water. But there is a constant rise in temperature when water reaches <em>its maximum capacity to react with these chemicals.</em>
Evidenced by the addition of 15 g and 20 g of chemicals, the temperature changes are constant
Answer:
The heat of formation of H2O(g) is likely to be-242,8KJ.
Explanation:
The heat of formation of H2O(g) will be slightly lower than the heat of formation of H2O(1)as some energy is released during condensation of water vapour to liquid water.