Answer:
Ice melting is a physical change. Physical changes are changes which affect the form of a chemical substance, but not its chemical composition. Certain factors, such as, temperature, contribute to the melting of ice, but it will be classified as a physical change, because the number of molecules present in the water does not change.
Explanation:
Answer:
Photoelectric effect, pair production and Compton scattering
Explanation:
Gamma rays, having no charge, can be slowed slowly by ionization as a material passes through. They suffer other mechanisms that eventually make them disappear, transferring their energy, they can cross several centimeters of a solid, or hundreds of meters of air, without undergoing any process or affecting the material they cross. Then they suffer one of the three effects and deposit much of their energy there. The three mechanisms of interaction with matter are: the photoelectric effect, the Compton effect and the production of pairs.
The photoelectric effect is that the photon meets an electron in the material and transfers all its energy, disappearing the original photon. The secondary electron acquires all the energy of the photon in the form of kinetic energy, and is sufficient to separate it from its atom and convert it into a projectile. This is stopped by ionization and excitation of the material
In the Compton effect the photon collides with an electron as if it were a clash between two elastic spheres. The secondary electron acquires only part of the energy of the photon and the rest takes it with another photon of lesser energy and diverted.
When an energy photon approaches the intense electric field of a nucleus, the production of pairs can happen. In this case the photon is transformed into an electron positron pair. Since the sum of the mass of the pair is 1.02 MeV, it cannot happen if the photon's energy is less than this amount. If the energy of the original photon is greater than 1.02 MeV, the surplus is distributed by the electron and the positron as kinetic energy, and the material can be ionized. The positron at the end of its path forms a positronium and then annihilates producing two annihilation photons, 0.51 MeV each.
A is Ea, which stands for activating energy. Energy is needed to get the reaction underway and Ea is the energy needed to “start” the reaction.
B is the temperature either released or absorbed.
The diagram shows that the reaction is exothermic based on the fact that the products energy is lower than the reactants. That is because energy (which is temperature in this case) is released during the process. If the reactants would have been lower than the products, the reaction would be endothermic.
Scientists tell people which issues are the most important describes an important role scientists have in society.
In addition to advising policymakers and other stakeholders about the best and wisest steps to take toward a human-centered society, scientists have a crucial role to play in preventing unwise and dangerous decisions. This promotes scientific knowledge and strengthens cross-cultural relationships and collaborative research. Additionally, they shouldn't overlook the objective, perpetually unfinished nature of science. With the help of a transdisciplinary cross-talks method, we emphasize the significance of information transfer across all scientific disciplines.
Due to the specific ways in which they aid in understanding how the world functions, scientists are crucial to society. It is a mode of thinking that helps us organize our knowledge in order to comprehend how things operate on a deeper level.
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Answer:
Buffer 1.
Explanation:
Ammonia is a weak base. It acts like a Bronsted-Lowry Base when it reacts with hydrogen ions.
.
gains one hydrogen ion to produce the ammonium ion 
. In other words, is the conjugate acid of the weak base .
Both buffer 1 and 2 include
- the weak base ammonia , and
- the conjugate acid of the weak base .
The ammonia in the solution will react with hydrogen ions as they are added to the solution:
.
There are more in the buffer 1 than in buffer 2. It will take more strong acid to react with the majority of in the solution. Conversely, the pH of buffer 1 will be more steady than that in buffer 2 when the same amount of acid has been added.
