(Originais Teachy 2023) - Question Medium of Sciences

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.

The lunar eclipse can also be called 'Blood Moon' due to its reddish color during the event. This coloration occurs due to the light from stars and planets passing through the Earth's atmosphere and reaching the lunar surface, being called diffuse light or twilight light. What are the main elements present in the Earth's atmosphere responsible for this coloration?

Imagine that our body is like a very large city, and the blood needs to reach all parts of this city to deliver oxygen and nutrients. The circulatory system is like the road network of this city, with the heart being the central pumping station and the veins and arteries being the avenues and streets through which the blood travels. Based on what you have learned about the circulatory system, explain how the heart, veins, and arteries work together to circulate blood through the body and mention at least one important function of each of these components.

In Brazil, the most frequent cancer is skin cancer, accounting for about 25% of all tumors diagnosed in all geographical regions. Natural ultraviolet radiation from the sun is its major etiological agent.