Answer:
Option d. 7
Explanation:
A mixture of a strong base and a strong acid produce a neutral salt and water.
This is the reaction of neutralization:
HCl + NaOH → NaCl + H₂O
NaCl → Na⁺ + Cl⁻
Sodium chloride is neutral salt which does not give H⁻ neither OH⁻ to medium, that's why pH is neutral.
Both ions are derivated from a strong acid and base so they do not make hydrolisis. They are a conjugate pair of a weak acid and base. The reactions can not occur:
Cl⁻ + H₂O ← OH⁻ + HCl
Na⁺ + H₃O⁺ ← NaOH + H₂O
Answer:
The nuclear decay of radioactive elements is a process that is a useful tool for determining the absolute age of fossils and rocks. It is used as a clock, in which daughter elements or isotopes converted from parent isotopes by decaying at a particular time.
Radioactive decay rates are constant and do not change over time. It is measured in half-life. A half-life is a time it takes half of a parent isotope to decay and converted into a stable daughter isotope. How many parent isotopes and daughter isotopes present in the fossil or their abundance can help in determining the age of fossil or rock.
Answer:
The correct answer is:
<em>(1) It is important that the sample is dissolved in just enough hot solvent. </em>
Explanation:
The process of recrystallization is important to eliminate the impurities and to obtain better crystals of the solid. The solvent used to perform the recrystallization must have a high dissolution power of the substance to be recrystallized and a low dissolution power of the impurities. This is in order to eliminate most impurities. Furthermore, <em>It is important that the sample is dissolved in just enough hot solvent </em>because this should be easy to remove after the recrystallization and the crystal should form easily when the solution cools. Also, it is better to add the hot solvent to solubilize the crystals and keep the impurities insoluble, instead of adding the cold solvent and heating the solution. Additionally, the process of cooling the solution must be done slowly to obtain large and fewer crystals. A fast ice-cooling will form smaller crystals.
<span>There are divergent boundaries where the plates are moving away from each other, causing magma to rise up. The boiling lava is almost immediately cooled and forms new sea floor crust.</span>
Answer:
Neils Bohr determined that electrons inhabit distinct energy levels.
Explanation: