(Originais Teachy 2023) - Question Medium of Sciences

In the solutions used in laboratories, the concentrations of ions $$\mathrm{H}_{3} \mathrm{O}^{+}$$ are usually small and a simple way to express the hydrogenionic concentration of a solution is through pH. Solutions of weak acids and bases present, in solution, an equilibrium between the various particles and, in this case, we have the equilibrium constant, that is, the ionization constant. A solution of $$1.10^{-3} \mathrm{mol}^{-1}$$ of bromoacetic acid $$\left(\mathrm{BrCH}_{2} \mathrm{CO}_{2} \mathrm{H}\right)$$ has an ionization constant equal to $$6.3.10^{-5} \mathrm{e}$$ and a solution of $$1.10^{-3} \mathrm{mol}^{-1}$$ of 4-chlorobenzoic acid $$\left(\mathrm{ClC}_{6} \mathrm{H}_{4} \mathrm{CO}_{2} \mathrm{H}\right)$$ has an ionization constant of $$1.0.10^{-4}$$. Given the following statements, I. 4-chlorobenzoic acid has a higher $$\mathrm{pH}$$ than bromoacetic acid. II. Bromoacetic acid is weaker than 4-chlorobenzoic acid. III. Since the concentrations are equal, both acids have the same $$\mathrm{pH}$$. IV. Bromoacetic acid has a higher $$\mathrm{pH}$$ than 4-chlorobenzoic acid. v. 4-chlorobenzoic acid is weaker than bromoacetic acid. It is verified that only ii and iv are correct.

Technological development has allowed the exploitation of natural resources in an increasingly intense way. However, this unrestrained exploitation has generated serious environmental problems. Deforestation is an example of these problems. Deforestation is the destruction of forest cover for agricultural use, urbanization, or timber extraction. Which of the following environmental impacts can be caused by deforestation?

Ionic bonds are formed when atoms or groups of atoms transfer or share electrons, resulting in the stabilization of the system's energy by minimizing these forces between the particles involved in the chemical reaction. Which of these factors directly influence the process of ionic bonding?

In the Folha de São Paulo newspaper, on June 14, 2013, a report was published about the chemical weapons attack in Syria "[...] Sarin gas is odorless and invisible. In addition to inhalation, simple contact with the skin of this organophosphorus gas affects the nervous system and causes death by cardiopulmonary arrest. The lethal dose for an adult is half a milligram. [...] Based on the information provided and chemical concepts, approximately how many molecules are there in an approximate lethal dose of sarin gas? Given: Consider the molar mass of sarin gas to be 140 g/mol. Avogadro's constant: 6.10^{23} entities.