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  • Ciências da Natureza

    Química

    Um grupo de pesquisadoras testava o efeito inibitório de extratos de um produto natural sobre a atividade de certa enzima envolvida em uma doença. A equipe preparou cinco extratos com mesmas quantidades do produto e condições de extração, alterando apenas o solvente: 

    Extrato 1 - Hexano; Extrato 2 - Etanoato de etila; Extrato 3 - Água; Extrato 4 - Solução aquosa de HCl 5 %; Extrato 5 - Solução aquosa de NaOH 5 %.

    Em seguida, foi feito o ensaio de inibição enzimática a 0,1 mg/mL de cada extrato, sendo obtido o gráfico abaixo: 

    Figura 1 de 2 da questão de Química, CEDERJ 2020, Propriedades Físicas dos Compostos Orgânicos: Polaridade das Ligações e Moléculas, Forças Intermoleculares, Ponto de Fusão e Ponto de Ebulição, Solubilização das Substâncias Orgânicas.

    Após novos estudos, as pesquisadoras notaram que o Extrato 2 continha todas as moléculas detectadas nos outros extratos com possível atividade inibitória. Suas estruturas são dadas a seguir: 

    Figura 2 de 2 da questão de Química, CEDERJ 2020, Propriedades Físicas dos Compostos Orgânicos: Polaridade das Ligações e Moléculas, Forças Intermoleculares, Ponto de Fusão e Ponto de Ebulição, Solubilização das Substâncias Orgânicas.

    Sabendo dessas informações, a alternativa que indica o provável composto responsável pelo efeito inibitório na enzima é:
    Escolha uma alternativa para a questão 62f0617f-8e
  • Ciências da Natureza

    Física

    Ao mudar-se de Salvador para Porto Seguro, Marina observou a mudança da rede elétrica, respectivamente, de 127 V para 220 V. Para a utilização de alguns equipamentos foi necessário a aquisição de transformadores, dispositivos que funcionam baseados no fenômeno da indução eletromagnética e têm a função de abaixar ou elevar a tensão elétrica.


    Com relação aos transformadores pode-se afirmar:
    Escolha uma alternativa para a questão 62f06c82-e6
  • Ciências da Natureza

    Química

    Analise a tabela de potenciais padrão de redução a seguir:

    Semirreação Eu (V)
    Al3+ (aq) + 3 e- ⇌ A I (s) -1,66
    Zn2+ (aq) + 2 e- ⇌ Zn (s) -0,76
    Fe2+ (aq) + 2 e- ⇌ Fe (s) -0,44
    Cu2+ (aq) + 2 e- ⇌ Cu (s) +0,34
    Ag+ (aq) + e- ⇌ A g (s) +0,80

    Com base na tabela, a afirmativa correta em relação ao processo de corrosão de metais é:
    Escolha uma alternativa para a questão 62f3168e-8e
  • Ciências da Natureza

    Química

    Alguns pensadores, fundamentados principalmente nas diferenças entre a natureza das leis e as teorias da Química e da Física, defendem a existência de uma filosofia específica para cada uma das ciências naturais. Assim, podemos pensar a filosofia da química com base em alguns fundamentos, sendo a Lei Periódica, proposta dos trabalhos de Meyer, Mendeleev e Moseley, um dos pilares de sustentação dessa filosofia.

    Assinale a alternativa CORRETA em relação à Lei Periódica.
    Escolha uma alternativa para a questão 62f3b433-70
  • Matemática

    Matemática

    Considere que no triângulo retângulo AOB, representado no sistema de eixos cartesianos ortogonais
    abaixo, tem-se yB > xA

    Imagem da questão de Matemática, PUC - SP 2011, Geometria Analítica Se o ponto P pertence às medianas do triângulo AOB, traçadas pelos vétices dos ângulos e cujas medidas são 15 e 3 √40 , então a equação da reta suporte do segmento AB é:

    Escolha uma alternativa para a questão 62f4be4a-26
  • Ciências da Natureza

    Física

    A radiação Ultravioleta é classificada em UVA, UVB, e UVC. Estas denominações foram introduzidas na década de 1930 pela Comissão Internacional de Iluminação. Estas classificações têm relação com os comprimentos de ondas, sendo a UVC a faixa mais energética, também chamada de radiação germicida por ser capaz de destruir os germes.

    OKUNO, E. e VILELA, M.A.C. Radiação Ultravioleta: características e efeitos. Ed.Livraria da Física SBF, 2005.


    Considerando que o menor comprimento de onda da radiação germicida é de 100 nm com, a correspondente frequência de 3,00 PHz, e que 1 nm =10-9 m e 1 PHz = 1015 Hz, pode-se afirmar que a velocidade desta onda eletromagnética, em 108 m/s, é:
    Escolha uma alternativa para a questão 62f4e3c8-e6
  • Ciências da Natureza

    Química

    A queima completa de combustíveis que contém carbono em sua composição gera dióxido de carbono, um dos principais gases responsáveis pelo fenômeno do aquecimento global. O uso de etanol como combustível em veículos automotivos é uma iniciativa que reduz a emissão de dióxido de carbono para a atmosfera.

    Considere a combustão completa de etanol suficiente para gerar um calor de 1.105 kJ.

    Imagem da questão de Química, CEDERJ 2020, Termoquímica: Energia Calorífica, Calor de reação, Entalpia, Equações e Lei de Hess.

            
    Com base na entalpia de formação aproximada dos compostos dados na tabela, a massa de gás carbônico, em kg, liberada nessa queima é de, aproximadamente:
    Escolha uma alternativa para a questão 62f5d930-8e
  • Ciências da Natureza

    Química

    O vinagre é um insumo presente na maioria das cozinhas de casas e restaurantes, cujo principal constituinte é o ácido acético (pKa = 5). Sua produção é feita pela fermentação alcoólica de um carboidrato, que pode vir, por exemplo, da maçã ou do arroz, por leveduras, gerando etanol como principal produto. Em seguida, é feita a fermentação acética do etanol por acetobactérias, convertendo-o a ácido acético.

    Considere que uma colher de sopa de vinagre com um teor de ácido acético de 3,0 % (m/v) foi misturada com 4 colheres de sopa de água para ser usada em limpeza. O valor de pH do vinagre após a diluição é de:
    Escolha uma alternativa para a questão 62f8ba76-8e
  • Ciências da Natureza

    Química

    Imagem da questão de Química, IF-BA 2012, Soluções e Substâncias Inorgânicas


    De acordo com as informações contidas na tabela sobre as propriedades físicas das substâncias listadas, é correto afirmar:

    Escolha uma alternativa para a questão 62f8da0d-e6
  • Ciências Humanas

    Geografia

    Imagem da questão de Geografia, UFMG 2007, Clima

    A partir dessa leitura e considerando-se outros conhecimentos sobre o assunto, é INCORRETO afrmar que
    Escolha uma alternativa para a questão 62f97e55-62
  • Ciências da Natureza

    Química

    A função orgânica dos ésteres é conhecida por sua aplicação como aditivos em alimentos que conferem fragrâncias e sabores artificiais. A tabela abaixo indica alguns ésteres e suas respectivas fragrâncias ou sabores associados.

    Éster Fragrância ou sabor
    Acetato de isoamila Banana
    Acetato de propila Pera
    2-metilbutanoato de etila Maçã verde
    2-metilpropanoato de propila Rum
    Hexanoato de alila Abacaxi
    Acetato de isobutila Framboesa

    Em um laboratório de química orgânica, foram feitas transformações com dois destes ésteres:

    I) O éster relativo à fragrância de abacaxi foi hidrolisado em meio ácido. O álcool formado sofreu uma hidrogenação catalítica, gerando o composto A.
    II) O éster relativo à fragrância de framboesa também foi hidrolisado em meio ácido. O álcool formado foi oxidado na presença de KMnO4/H2SO4, gerando o composto B.

    A alternativa que mostra a fragrância do éster formado pela reação entre os compostos AeBem meio ácido é:
    Escolha uma alternativa para a questão 62fb8fe4-8e
  • Ciências da Natureza

    Biologia

    A hipófise possui 2 lobos bem desenvolvidos: o anterior ou adenoipófise, e o posterior ou neuroipófise. São hormônios produzidos pela adenoipófise:
    Escolha uma alternativa para a questão 62fd9502-70
  • Ciências da Natureza

    Química

    Na Natureza, há uma gama enorme de pares de compostos isômeros que são estereoisômeros.Eles possuem propriedades físicas idênticas, como ponto de fusão e ponto de ebulição, e diferem na capacidade de desviar o plano da luz polarizada em sentidos opostos. A seguir, estão representados dois destes estereoisômeros:

    Imagem da questão de Química, IF-BA 2012, Cadeias Carbônicas: Características e Classificações do Átomo do Carbono, Tipos de Ligação e Hibridação. Tipos de Cadeias Carbônicas e Fórmulas. Séries: Homóloga, Isóloga e Heteróloga.

    Analisando as estruturas dos isômeros do aspartame, é correto afirmar:
    Escolha uma alternativa para a questão 62fe1f3f-e6
  • Linguagens

    Inglês

    What about the artists?

    The Guardian - Wed 14 Oct 2020


    The government is deaf to the plight of freelance musicians and othercreatives


          On Monday, a number of British arts organisations finally heard whether they had received grants from the £1.57bn bailout fund announced in July by the chancellor, Rishi Sunak. Not a moment too soon, institutions such as Wigmore Hall in London, Bristol Old Vic and the City of Birmingham Symphony Orchestra have been given a cash bufferthatshould keep them alive until March.

         The welcome announcement has been marred, though, by the failure of the government to address the question of freelancers and self-employed people in the arts. In an interview with ITV last week, Mr. Sunak was asked what he thought professional musicians ought to do, given that they can’t earn enough to live. He answered that up to 3 million people in the country qualified for help under the self-employed support scheme. Pressed on whether musicians oughttofind differentwork, he mentioned retraining schemes that are "providing new and fresh opportunity”. People must adapt, he said. He added that it was untrue that there was no work for musicians. Music lessons, in his own household at least, were still going on.

         The interviewer’s question was specifically about musicians - a third of whom have been ineligible for the selfemployed support scheme. So even if, as he later asserted, Mr Sunak was talking about the workforce as a whole rather than cultural workers in particular when he spoke of the need to retrain, he certainly gave a strong impression of indifference to and ignorance of musicians’ plight. This was reinforced on Monday when a government-backed advertisement went viral, launching hundreds of derisive parodies. Aiming to recruit workers into cybersecurity roles, it showed a dancer doing up her ballet shoes. It read: "Fatima’s next job could be in cyber (she just doesn’t know it yet)”. 
         The culture secretary, Oliver Dowden, was forced to condemn the advertisement as "crass” as his day of good news descended into farce and contumely. The government seems unable to grasp that putting money into the arts infrastructure is only part of the solution; creatives themselves need to be helped to survive economically too. Though some institutions are putting work on stage - and will be helped to do so in the months to come by the rescue package - these events will necessarily be small-scale, representing a drop in the ocean compared with the industry working at full tilt.
         New digital business models are being explored, but they are in their infancy and are not going to pay next month’s rent. Moreover, performance dates in the diary - that is, employment opportunities for freelancers - amount to perilous bets against the future course of the virus. As infections soar, organisations are bound, quite rightly, to be cautious, particularly in the face of the catastrophic failure of the government’s test-and-trace scheme.
         Meanwhile, musicians and others are certainly "adapting” - often to unskilled, low-paid work, though there is not much of that to go around. The government’s continued implication that musicians and other creative workers - many of whom have trained since childhood for some of the most demanding, competitive and highly skilled work in the economy - are somehow not "viable” is both insulting and ignorant. Underlying Mr Sunak’s remarks was the tired old Tory notion that creative jobs are not "real jobs”, and are undertaken by some fantastical species who are not, in fact, real people. Perhaps the chancellor should ask his family’s music teacher what it’s really like for artists right now - and actually listen to the answer.

    Source: The Guardian, available at https://www.theguardian. com/commentisfree/2020/oct/14/the-guardian-view-on-saving-thearts-what-about-the-artists, accessed on October21st, 2020.

    The opinion editorial above advances the following position:
    Escolha uma alternativa para a questão 62fe86b3-8e
  • Ciências da Natureza

    Química

    No início da pandemia da COVID-19, diversas fake news foram divulgadas em aplicativos e redes sociais, visando causar desinformação e confundir as pessoas. Uma das notícias falsas foi apresentada em vídeo de curta duração, no qual um indivíduo se apresenta como funcionário de uma indústria química ensinando a produzir um vapor alcalino, que seria eficaz no combate à doença. No filme, ao misturar dois copos de água da torneira com uma colher pequena de bicarbonato de sódio (NaHCO3) e aquecer em fogão caseiro, essa mistura libera um vapor alcalino quando o ponto de ebulição do sal estiver próximo, capaz de derreter o novo coronavírus, que possui características ácidas.

    Assinale a alternativa que justifica, do ponto de vista químico, as razões para a informação do vídeo ser equivocada.
    Escolha uma alternativa para a questão 62feca7f-70
  • Linguagens

    Inglês

    What about the artists?

    The Guardian - Wed 14 Oct 2020


    The government is deaf to the plight of freelance musicians and othercreatives


          On Monday, a number of British arts organisations finally heard whether they had received grants from the £1.57bn bailout fund announced in July by the chancellor, Rishi Sunak. Not a moment too soon, institutions such as Wigmore Hall in London, Bristol Old Vic and the City of Birmingham Symphony Orchestra have been given a cash bufferthatshould keep them alive until March.

         The welcome announcement has been marred, though, by the failure of the government to address the question of freelancers and self-employed people in the arts. In an interview with ITV last week, Mr. Sunak was asked what he thought professional musicians ought to do, given that they can’t earn enough to live. He answered that up to 3 million people in the country qualified for help under the self-employed support scheme. Pressed on whether musicians oughttofind differentwork, he mentioned retraining schemes that are "providing new and fresh opportunity”. People must adapt, he said. He added that it was untrue that there was no work for musicians. Music lessons, in his own household at least, were still going on.

         The interviewer’s question was specifically about musicians - a third of whom have been ineligible for the selfemployed support scheme. So even if, as he later asserted, Mr Sunak was talking about the workforce as a whole rather than cultural workers in particular when he spoke of the need to retrain, he certainly gave a strong impression of indifference to and ignorance of musicians’ plight. This was reinforced on Monday when a government-backed advertisement went viral, launching hundreds of derisive parodies. Aiming to recruit workers into cybersecurity roles, it showed a dancer doing up her ballet shoes. It read: "Fatima’s next job could be in cyber (she just doesn’t know it yet)”. 
         The culture secretary, Oliver Dowden, was forced to condemn the advertisement as "crass” as his day of good news descended into farce and contumely. The government seems unable to grasp that putting money into the arts infrastructure is only part of the solution; creatives themselves need to be helped to survive economically too. Though some institutions are putting work on stage - and will be helped to do so in the months to come by the rescue package - these events will necessarily be small-scale, representing a drop in the ocean compared with the industry working at full tilt.
         New digital business models are being explored, but they are in their infancy and are not going to pay next month’s rent. Moreover, performance dates in the diary - that is, employment opportunities for freelancers - amount to perilous bets against the future course of the virus. As infections soar, organisations are bound, quite rightly, to be cautious, particularly in the face of the catastrophic failure of the government’s test-and-trace scheme.
         Meanwhile, musicians and others are certainly "adapting” - often to unskilled, low-paid work, though there is not much of that to go around. The government’s continued implication that musicians and other creative workers - many of whom have trained since childhood for some of the most demanding, competitive and highly skilled work in the economy - are somehow not "viable” is both insulting and ignorant. Underlying Mr Sunak’s remarks was the tired old Tory notion that creative jobs are not "real jobs”, and are undertaken by some fantastical species who are not, in fact, real people. Perhaps the chancellor should ask his family’s music teacher what it’s really like for artists right now - and actually listen to the answer.

    Source: The Guardian, available at https://www.theguardian. com/commentisfree/2020/oct/14/the-guardian-view-on-saving-thearts-what-about-the-artists, accessed on October21st, 2020.

    The "3 million people in the country qualified for help under the self-employed support scheme” (2nd paragraph) includes the following group of people:
    Escolha uma alternativa para a questão 63019382-8e
  • Ciências da Natureza

    Química

    A ureia reage com a amônia líquida, formando um sal de amônio

    Imagem da questão de Química, IF-BA 2012, Equilíbrio Químico

    Sobre a natureza das interações entre as espécies envolvidas na reação, o comportamento químico das substâncias reagentes e o átomo de nitrogênio, é correto afirmar:
    Escolha uma alternativa para a questão 6303d2bc-e6
  • Linguagens

    Inglês

    What about the artists?

    The Guardian - Wed 14 Oct 2020


    The government is deaf to the plight of freelance musicians and othercreatives


          On Monday, a number of British arts organisations finally heard whether they had received grants from the £1.57bn bailout fund announced in July by the chancellor, Rishi Sunak. Not a moment too soon, institutions such as Wigmore Hall in London, Bristol Old Vic and the City of Birmingham Symphony Orchestra have been given a cash bufferthatshould keep them alive until March.

         The welcome announcement has been marred, though, by the failure of the government to address the question of freelancers and self-employed people in the arts. In an interview with ITV last week, Mr. Sunak was asked what he thought professional musicians ought to do, given that they can’t earn enough to live. He answered that up to 3 million people in the country qualified for help under the self-employed support scheme. Pressed on whether musicians oughttofind differentwork, he mentioned retraining schemes that are "providing new and fresh opportunity”. People must adapt, he said. He added that it was untrue that there was no work for musicians. Music lessons, in his own household at least, were still going on.

         The interviewer’s question was specifically about musicians - a third of whom have been ineligible for the selfemployed support scheme. So even if, as he later asserted, Mr Sunak was talking about the workforce as a whole rather than cultural workers in particular when he spoke of the need to retrain, he certainly gave a strong impression of indifference to and ignorance of musicians’ plight. This was reinforced on Monday when a government-backed advertisement went viral, launching hundreds of derisive parodies. Aiming to recruit workers into cybersecurity roles, it showed a dancer doing up her ballet shoes. It read: "Fatima’s next job could be in cyber (she just doesn’t know it yet)”. 
         The culture secretary, Oliver Dowden, was forced to condemn the advertisement as "crass” as his day of good news descended into farce and contumely. The government seems unable to grasp that putting money into the arts infrastructure is only part of the solution; creatives themselves need to be helped to survive economically too. Though some institutions are putting work on stage - and will be helped to do so in the months to come by the rescue package - these events will necessarily be small-scale, representing a drop in the ocean compared with the industry working at full tilt.
         New digital business models are being explored, but they are in their infancy and are not going to pay next month’s rent. Moreover, performance dates in the diary - that is, employment opportunities for freelancers - amount to perilous bets against the future course of the virus. As infections soar, organisations are bound, quite rightly, to be cautious, particularly in the face of the catastrophic failure of the government’s test-and-trace scheme.
         Meanwhile, musicians and others are certainly "adapting” - often to unskilled, low-paid work, though there is not much of that to go around. The government’s continued implication that musicians and other creative workers - many of whom have trained since childhood for some of the most demanding, competitive and highly skilled work in the economy - are somehow not "viable” is both insulting and ignorant. Underlying Mr Sunak’s remarks was the tired old Tory notion that creative jobs are not "real jobs”, and are undertaken by some fantastical species who are not, in fact, real people. Perhaps the chancellor should ask his family’s music teacher what it’s really like for artists right now - and actually listen to the answer.

    Source: The Guardian, available at https://www.theguardian. com/commentisfree/2020/oct/14/the-guardian-view-on-saving-thearts-what-about-the-artists, accessed on October21st, 2020.

    The second and first paragraphs are linked by a notion of contrast, which is explicitly conveyed by the linking word "though” (2nd paragraph). The contrast refers to the difference in treatment between::
    Escolha uma alternativa para a questão 63043f53-8e
  • Ciências da Natureza

    Química

    Conhecer a estrutura cristalina é de fundamental importância para explicar as propriedades físicas de um material. Em alguns casos, é possível mudar a estrutura cristalina do material, submetendo-o a certas condições de pressão e temperatura. Por exemplo, abaixo de 912 °C, o ferro metálico tem forma cristalina chamada de reticulado cúbico de corpo centrado (CCC). No entanto, entre 912 ºC e 1394 °C, a forma cristalina muda para reticulado cúbico de face centrada (CFC). Em função das diferenças nas propriedades físicas e químicas dessas espécies, elas são denominadas de Ferro-α e Ferro-γ, respectivamente.

    Assinale a alternativa que apresenta o nome do fenômeno descrito no texto acima.
    Escolha uma alternativa para a questão 6304ab81-70
  • Linguagens

    Inglês

    What about the artists?

    The Guardian - Wed 14 Oct 2020


    The government is deaf to the plight of freelance musicians and othercreatives


          On Monday, a number of British arts organisations finally heard whether they had received grants from the £1.57bn bailout fund announced in July by the chancellor, Rishi Sunak. Not a moment too soon, institutions such as Wigmore Hall in London, Bristol Old Vic and the City of Birmingham Symphony Orchestra have been given a cash bufferthatshould keep them alive until March.

         The welcome announcement has been marred, though, by the failure of the government to address the question of freelancers and self-employed people in the arts. In an interview with ITV last week, Mr. Sunak was asked what he thought professional musicians ought to do, given that they can’t earn enough to live. He answered that up to 3 million people in the country qualified for help under the self-employed support scheme. Pressed on whether musicians oughttofind differentwork, he mentioned retraining schemes that are "providing new and fresh opportunity”. People must adapt, he said. He added that it was untrue that there was no work for musicians. Music lessons, in his own household at least, were still going on.

         The interviewer’s question was specifically about musicians - a third of whom have been ineligible for the selfemployed support scheme. So even if, as he later asserted, Mr Sunak was talking about the workforce as a whole rather than cultural workers in particular when he spoke of the need to retrain, he certainly gave a strong impression of indifference to and ignorance of musicians’ plight. This was reinforced on Monday when a government-backed advertisement went viral, launching hundreds of derisive parodies. Aiming to recruit workers into cybersecurity roles, it showed a dancer doing up her ballet shoes. It read: "Fatima’s next job could be in cyber (she just doesn’t know it yet)”. 
         The culture secretary, Oliver Dowden, was forced to condemn the advertisement as "crass” as his day of good news descended into farce and contumely. The government seems unable to grasp that putting money into the arts infrastructure is only part of the solution; creatives themselves need to be helped to survive economically too. Though some institutions are putting work on stage - and will be helped to do so in the months to come by the rescue package - these events will necessarily be small-scale, representing a drop in the ocean compared with the industry working at full tilt.
         New digital business models are being explored, but they are in their infancy and are not going to pay next month’s rent. Moreover, performance dates in the diary - that is, employment opportunities for freelancers - amount to perilous bets against the future course of the virus. As infections soar, organisations are bound, quite rightly, to be cautious, particularly in the face of the catastrophic failure of the government’s test-and-trace scheme.
         Meanwhile, musicians and others are certainly "adapting” - often to unskilled, low-paid work, though there is not much of that to go around. The government’s continued implication that musicians and other creative workers - many of whom have trained since childhood for some of the most demanding, competitive and highly skilled work in the economy - are somehow not "viable” is both insulting and ignorant. Underlying Mr Sunak’s remarks was the tired old Tory notion that creative jobs are not "real jobs”, and are undertaken by some fantastical species who are not, in fact, real people. Perhaps the chancellor should ask his family’s music teacher what it’s really like for artists right now - and actually listen to the answer.

    Source: The Guardian, available at https://www.theguardian. com/commentisfree/2020/oct/14/the-guardian-view-on-saving-thearts-what-about-the-artists, accessed on October21st, 2020.

    Considering the expression of happenings in the past, verbs vary following time precision or imprecision. The example extracted from the editorial that reflects unspecified time is:
    Escolha uma alternativa para a questão 6306fb07-8e