Answer:
B) it is endothermic and the temperature decreased
Explanation:
Chemical reactions can be classified as endothermic and exothermic.
Endothermic reactions proceed with the absorption of heat energy (q) and have a positive value for q.
In contrast, Exothermic reactions proceed with the liberation of heat energy (q) and have a negative value for q.
It is given that the value of q = +450 J. Since q is positive, this implies that heat energy is absorbed from the surroundings resulting in a fall in temperature. Hence the reaction is endothermic.
Ionic bond
Na+ has a POSITIVE charge
while Cl- has a NEGATIVE one.
Through ionic bond both form NACL (Salt).
Answer: option A. the colors absorbed when an element gains energy.
Justification:
The electromagnetic waves, visible light included, consists of a gamma of waves with different frequencies and wavelengths.
The visible light can be decomposed in a set of series of lines of light with different frequencies and that decomposition is what a spectrum of light is. Each series correspond to a color.
The atoms can absorb and emit photons. That is, atoms can absorb and release energy.
When the atom abosorbs a photon an electron gets excited ( the electron gains energy).
The light absorbed, then, corresponds to color absortion, and the spectrum of absortion is the colors absorbed by the atom when its electrons gain energy by the absortion of photons (light).
