Foram encontradas 50 questões.
Uma massa equivalente a 25,48 g de nitrato de amônio foi dissolvida em água destilada utilizando-se um balão volumétrico de 250 mL; o volume foi completado e a solução homogeneizada. Qual é a concentração de mols/L e g/L da solução final? (Considere: massa molar NH4NO3 = 80 g/mol.)
Provas
Uma solução com exatamente 1,5000 g de sulfato de cobre foi tratada com excesso de cloreto de bário. O sal produzido foi corretamente tratado, lavado, transferido para um cadinho e mantido em estufa a 70°C, até que sua massa ficasse com um valor constante e igual a 19,5320 g. Após a massa se tornar constante, o cadinho e o sal foram calcinados em mufla e, a massa do cadinho e a massa do resíduo calcinado ficaram com 18,7735 g. Assinale a alternativa que contém, respectivamente, a porcentagem de água no sal formado e o número de mols de água de cristalização por mol do sal.
(Considere: massas atômicas (g/mol) Cu = 63,55; O = 16,00; S = 32,01; Ba = 137,33; Cl = 35,5; H = 1,01.)
Provas
Trabalhar com segurança em laboratórios é ponto fundamental para preservar a saúde dos usuários e o meio ambiente. Os riscos potenciais devem ser anulados ou minimizados. Sobre regras de segurança, analise as afirmativas.
I. Não se deve comer e/ou beber dentro do laboratório.
II. Na diluição de ácidos, deve-se adicionar sempre a água ao ácido; nunca o inverso.
III. Na incerteza sobre o material químico com o qual se trabalha, deve-se usar os sentidos para tentar identificá-lo. Assim, pode-se provar ou cheirar o produto.
IV. É necessário conhecer e utilizar corretamente o material de laboratório.
V. Deve-se verificar bem o rótulo dos frascos, as indicações inscritas, especialmente, os símbolos de aviso.
VI. Não se deve misturar substâncias ao acaso.
VII. Pode-se fumar dentro do laboratório, somente nos locais permitidos.
VIII. Não sentar ou debruçar na bancada, e nem sentar no chão.
IX. Não usar o mesmo equipamento volumétrico para medir simultaneamente soluções diferentes.
X. As experiências que provocam a libertação de vapores tóxicos podem ser feitas em qualquer local do laboratório.
Estão INCORRETAS apenas as afirmativas
Provas
Devido ao aumento da preocupação ambiental global, tem-se monitorado cada dia mais a qualidade das águas dos rios e fontes de água doce. A qualidade da água deve ter os seus parâmetros químicos, físicos e biológicos monitorados. Em relação aos parâmetros químicos devem ser analisados, entre outros, pH, dureza, componentes orgânicos e inorgânicos, demandas químicas e bioquímicas de oxigênio e oxigênio dissolvido (OD). A quantidade de oxigênio dissolvido na água é indispensável para a sobrevivência de organismos aeróbios e o seu teor de saturação depende da altitude e da temperatura onde se encontra a fonte. Uma forma barata e simples de determinar a concentração de oxigênio molecular dissolvido na água é mergulhar um pedaço de palha de aço em exatamente 1 litro de água, por 5 dias em um recipiente completamente lacrado para evitar a entrada de oxigênio atmosférico. Sabe-se que um técnico realizou este procedimento e observou que o pedaço de palha de aço estava completamente enferrujado e a massa da ferrugem (Fe2O3) formada foi 50 mg. Determine a concentração, em mols/L, e a porcentagem de O2 na água analisada, sabendo-se que a reação que ocorreu entre o oxigênio da água e o ferro da palha de aço é 2Fe (s) + 3/2O2(g) → Fe2O3 (g). (Considere: massas molares (g/mol) Fe = 55,85; O = 16,00.)
Assinale a alternativa que contém, respectivamente o valor da concentração (mols/L) do O2 e a sua percentagem (m/v) na água.
Provas
Science and the olympics: technology's increasing role in the games
People used to rarely associate science with sports, but increased engineering research and investment in technology by professional sporting organizations have merged the two industries, especially in the 2012 London Olympics.
Scientists and engineers played a significant role in shaping the Great Britain Olympic team, according to BBC News. Though the partnership between sports and science has been a relatively new development, the impact of it can be seen across a number of different events.
Mobile technology, smartphones and tablet computers are found in droves at the London Olympics, as coaches, players and country officials can be seen using these devices to gauge and improve their performance.
According to the news outlet, the ease with which these devices can be integrated into sports has been surprising, but the results are hard to ignore.
(http://why.knovel.com/all-engineering-news/1752-science-and-the-olympics-technologys-increasing-role-in-the-games.html – Com adaptações.)
The conjunction highlighted in “Though the partnership between sports and science has been a relatively new development…” could be replaced, without change of meaning, by
Provas
Science and the olympics: technology's increasing role in the games
People used to rarely associate science with sports, but increased engineering research and investment in technology by professional sporting organizations have merged the two industries, especially in the 2012 London Olympics.
Scientists and engineers played a significant role in shaping the Great Britain Olympic team, according to BBC News. Though the partnership between sports and science has been a relatively new development, the impact of it can be seen across a number of different events.
Mobile technology, smartphones and tablet computers are found in droves at the London Olympics, as coaches, players and country officials can be seen using these devices to gauge and improve their performance.
According to the news outlet, the ease with which these devices can be integrated into sports has been surprising, but the results are hard to ignore.
(http://why.knovel.com/all-engineering-news/1752-science-and-the-olympics-technologys-increasing-role-in-the-games.html – Com adaptações.)
The passive voice in “Mobile technology, smartphones and tablet computers are found in droves at the London Olympics” in the active voice is
Provas
Science and the olympics: technology's increasing role in the games
People used to rarely associate science with sports, but increased engineering research and investment in technology by professional sporting organizations have merged the two industries, especially in the 2012 London Olympics.
Scientists and engineers played a significant role in shaping the Great Britain Olympic team, according to BBC News. Though the partnership between sports and science has been a relatively new development, the impact of it can be seen across a number of different events.
Mobile technology, smartphones and tablet computers are found in droves at the London Olympics, as coaches, players and country officials can be seen using these devices to gauge and improve their performance.
According to the news outlet, the ease with which these devices can be integrated into sports has been surprising, but the results are hard to ignore.
(http://why.knovel.com/all-engineering-news/1752-science-and-the-olympics-technologys-increasing-role-in-the-games.html – Com adaptações.)
The main idea of the first paragraph is that
Provas
Mechanical engineers develop an “intelligent co-pilot” for cars
Semiautonomous system takes the wheel to keep drivers safe.
Jennifer Chu, MIT News Office
July 13, 2012
Barrels and cones dot an open field in Saline, Mich., forming an obstacle course for a modified vehicle. A driver remotely steers the vehicle through the course from a nearby location as a researcher looks on. Occasionally, the researcher instructs the driver to keep the wheel straight – a trajectory that appears to put the vehicle on a collision course with a barrel. Despite the driver’s actions, the vehicle steers itself around the obstacle, transitioning control back to the driver once the danger has passed.
The key to the maneuver is a new semiautonomous safety system developed by Sterling Anderson, a PhD student in MIT’s Department of Mechanical Engineering, and Karl Lagnemma, a principal research scientist in MIT’s Robotic Mobility Group.
The system uses an onboard camera and laser rangefinder to identify hazards in a vehicle’s environment. The team devised an algorithm to analyze the data and identify safe zones – avoiding, for example, barrels in a field, or other cars on a roadway. The system allows a driver to control the vehicle, only taking the wheel when the driver is about to exit a safe zone.
Anderson, who has been testing the system in Michigan since last September, describes it as an “intelligent co-pilot” that monitors a driver’s performance and makes behind-the-scenes adjustments to keep the vehicle from colliding with obstacles, or within a safe region of the environment, such as a lane or open area.
“The real innovation is enabling the car to share (control) with you,” Anderson says. “If you want to drive, it’ll just… make sure you don’t hit anything.”
The group presented details of the safety system recently at the Intelligent Vehicles Symposium in Spain.
(http://web.mit.edu/newsoffice/2012/mechanical-engineers-develop-intelligent-car-co-pilot-0713.html – Com adaptações.)
Mark the alternative that presents the correct relation between the fragment and the brackets.
I. “Anderson, who has been testing the system in Michigan since last September, describes it as an ‘intelligent copilot’ that monitors a driver’s performance…” (Anderson)
II. “… the researcher instructs the driver to keep the wheel straight – a trajectory that appears to put the vehicle on a collision course with a barrel.” (trajectory)
III. “Anderson, who has been testing the system in Michigan since last September, describes it as an ‘intelligent copilot’ that monitors a driver’s performance” (co-pilot)
Provas
Mechanical engineers develop an “intelligent co-pilot” for cars
Semiautonomous system takes the wheel to keep drivers safe.
Jennifer Chu, MIT News Office
July 13, 2012
Barrels and cones dot an open field in Saline, Mich., forming an obstacle course for a modified vehicle. A driver remotely steers the vehicle through the course from a nearby location as a researcher looks on. Occasionally, the researcher instructs the driver to keep the wheel straight – a trajectory that appears to put the vehicle on a collision course with a barrel. Despite the driver’s actions, the vehicle steers itself around the obstacle, transitioning control back to the driver once the danger has passed.
The key to the maneuver is a new semiautonomous safety system developed by Sterling Anderson, a PhD student in MIT’s Department of Mechanical Engineering, and Karl Lagnemma, a principal research scientist in MIT’s Robotic Mobility Group.
The system uses an onboard camera and laser rangefinder to identify hazards in a vehicle’s environment. The team devised an algorithm to analyze the data and identify safe zones – avoiding, for example, barrels in a field, or other cars on a roadway. The system allows a driver to control the vehicle, only taking the wheel when the driver is about to exit a safe zone.
Anderson, who has been testing the system in Michigan since last September, describes it as an “intelligent co-pilot” that monitors a driver’s performance and makes behind-the-scenes adjustments to keep the vehicle from colliding with obstacles, or within a safe region of the environment, such as a lane or open area.
“The real innovation is enabling the car to share (control) with you,” Anderson says. “If you want to drive, it’ll just… make sure you don’t hit anything.”
The group presented details of the safety system recently at the Intelligent Vehicles Symposium in Spain.
(http://web.mit.edu/newsoffice/2012/mechanical-engineers-develop-intelligent-car-co-pilot-0713.html – Com adaptações.)
Each verb tense presents verb aspects which reveal what we want to express about the point in time the action takes place. The highlighted verb tense in “The system uses an onboard camera and laser rangefinder…” expresses
Provas
Mechanical engineers develop an “intelligent co-pilot” for cars
Semiautonomous system takes the wheel to keep drivers safe.
Jennifer Chu, MIT News Office
July 13, 2012
Barrels and cones dot an open field in Saline, Mich., forming an obstacle course for a modified vehicle. A driver remotely steers the vehicle through the course from a nearby location as a researcher looks on. Occasionally, the researcher instructs the driver to keep the wheel straight – a trajectory that appears to put the vehicle on a collision course with a barrel. Despite the driver’s actions, the vehicle steers itself around the obstacle, transitioning control back to the driver once the danger has passed.
The key to the maneuver is a new semiautonomous safety system developed by Sterling Anderson, a PhD student in MIT’s Department of Mechanical Engineering, and Karl Lagnemma, a principal research scientist in MIT’s Robotic Mobility Group.
The system uses an onboard camera and laser rangefinder to identify hazards in a vehicle’s environment. The team devised an algorithm to analyze the data and identify safe zones – avoiding, for example, barrels in a field, or other cars on a roadway. The system allows a driver to control the vehicle, only taking the wheel when the driver is about to exit a safe zone.
Anderson, who has been testing the system in Michigan since last September, describes it as an “intelligent co-pilot” that monitors a driver’s performance and makes behind-the-scenes adjustments to keep the vehicle from colliding with obstacles, or within a safe region of the environment, such as a lane or open area.
“The real innovation is enabling the car to share (control) with you,” Anderson says. “If you want to drive, it’ll just… make sure you don’t hit anything.”
The group presented details of the safety system recently at the Intelligent Vehicles Symposium in Spain.
(http://web.mit.edu/newsoffice/2012/mechanical-engineers-develop-intelligent-car-co-pilot-0713.html – Com adaptações.)
The word “driver” in “… a driver remotely steers the vehicle through the course…” is formed by the verb ‘drive’ and the suffix ‘-er’, which denotes occupation or profession. Mark the alternative which presents a similar case.
Provas
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