When two substances are mixed and light is produced is it a chemical or physical change?

When an iron nail rusts it seems to get heavier in mass. Does the iron nail follow the law of conservation of mass? A. no rusting is an exception to the law of conservation of mass. B.

Write a formula for the compound that forms between sodium and each polyatomic ion:

Whch compounds is most reactive toward nucleophilic acyl substitution?

Compared with Earth, the Moon has a surface that is geologically less active. For example A. both the Moon and the Earth have continents that move around. B. the Moon has many active volcanoes, while the Earth has none. C.

How much heat (kJ) is absorbed from water in order for 5.50 moles NH4NO3 to dissolve in water?

A compound that changes color when it comes into contact with an acid or base is an?

1. A food sample is burned in a calorimeter that contains 2000. g of water. The temperature increases from 22.0°C to 44.3 °C. How many Calories does the food sample contain, assuming all of the energy from the food was transferred into the water?

Why doesn't water light on fire? It has all the ingredients except heat! Hydrogen for the flammability factor, oxygen so it can keep burning, and all you need to do is add heat and BOOM you have a flame! 15 pts

The type of social bonds present in modern societies that are based on difference, interdependence, and individual rights is called:

The difference between ionic covalent and metallic bonding