The atoms in a sample of an element are in excited states. a bright-line spectrum is produced when these atoms a. absorb energy b. absorb positrons c. emit energy d. emit positrons

The correct answer is C. To produce a bright-line spectrum, atoms will need to give off energy to then show this light. Emit means to give something off externally, so the answer is emit energy. A is incorrect because absorbing energy would be the opposite of C, because the atoms would be taking in rather than giving off light. Also, light is a form of energy, not a positron (which has the same mass as an electron but with a positive charge), making both B and D incorrect.

Reactants are more stable in the given reaction.

Explanation:

When heat is absorbed by reactant species from the surrounding then it is known as an endothermic reaction. In an endothermic reaction, energy of reactants is less than the energy of products.

It is known that when energy of a substance is more then it is considered as unstable and when energy of a substance is less then is is considered as stable.

So, when is positive then it means heat is absorbed by the system. And when   is negative then it means heat is released by the system.

Therefore, we can conclude that in the given reaction reactants are more stable than products.