Foram encontradas 4.889 questões
Resolva questões gratuitamente!
Junte-se a mais de 4 milhões de concurseiros!
Considerando a dissociação de um ácido genérico (HA) em água, conforme a equação mostrada acima, identifique como verdadeiras (V) ou falsas (F) as seguintes afirmativas:
( ) Se HA = HCl, ele estará completamente dissociado e a [H3O+ ] = [HCl]inicial. ( ) HA é o ácido conjugado da H2O enquanto H3O+ é o ácido conjugado de A- . ( ) HA é um ácido de Bronsted-Lowry e H2O é uma base de Bronsted-Lowry. ( ) Se HA = ácido acético, ele estará completamente dissociado e a [H3O+ ] = [ácido acético]inicial.
Assinale a alternativa que apresenta a sequência correta, de cima para baixo.

Assumindo que as equações acima são modelos que podem ser aplicados a qualquer reação química, é correto afirmar que, no equilíbrio:
1. as concentrações de A, B, C e D são iguais. 2. as concentrações de A, B, C e D não se alteram com o tempo. 3. a reação para de acontecer, logo, a formação de produtos é interrompida. 4. a constante de velocidade da reação direta (k1) é igual à da reação inversa (k-1).
Assinale a alternativa correta.
5 Fe2+(aq) + MnO4-(aq) + 8 H+(aq) → 5 Fe3+(aq) + Mn2+(aq) + 8 H2O(aq)
O ponto estequiométrico é atingido quando todo o Fe2+ reagiu, e a detecção é feita quando a cor característica da solução contendo íons MnO4- persiste. Para dissolver uma amostra de 202 mg de minério em ácido clorídrico, foram necessários 16,7 mL de uma solução 1,08 x 10-2 mol L-1 de KMnO4 para atingir o ponto estequiométrico. Qual é a porcentagem em massa de ferro na amostra?
C6H12O6(aq) → C2H6O(aq) + CO2(g)
(Massas molares (g mol-1 ): C = 12; H = 1; O = 16)
Qual é a massa, em gramas, de CO2 produzida quando 0,400 mol de glicose reage dessa maneira?
Com relação a decaimento, considere as seguintes equações:


São equações de decaimento:

Supondo que os elementos A, D, X, Z e J possam ocorrer na forma de isótopos, e com base nas informações contidas na tabela, é correto afirmar que:
A molécula orgânica ceteno (C2H2O) tem a seguinte estrutura de Lewis:

INSTRUCTION: Read the abstract and answer to the question.
Abstract
Scientists know greenhouse gas emissions cause climate change, but what causes greenhouse gas emissions in the first place? We assessed how many greenhouse gases are released to support the lifestyles of people living in different parts of Europe – in other words, we figured out people’s carbon footprint. We found that different lifestyle choices resulted in very different carbon footprints. In general, people with higher incomes (_____ bought more things and traveled more) had much higher carbon footprints than people ______ lived more modestly.
Understanding how our purchases affect greenhouse gas emissions is an important step to designing policies and guidelines for cutting emissions and addressing climate change.
Available at: <http://www.sciencejournalforkids.org/ uploads/5/4/2/8/54289603/footprint_article.pdf>.
Accessed on: Dec 7th, 2017.
The verb figure out can be replaced by:
INSTRUCTION: Read the abstract and answer to the question.
Abstract
Scientists know greenhouse gas emissions cause climate change, but what causes greenhouse gas emissions in the first place? We assessed how many greenhouse gases are released to support the lifestyles of people living in different parts of Europe – in other words, we figured out people’s carbon footprint. We found that different lifestyle choices resulted in very different carbon footprints. In general, people with higher incomes (_____ bought more things and traveled more) had much higher carbon footprints than people ______ lived more modestly.
Understanding how our purchases affect greenhouse gas emissions is an important step to designing policies and guidelines for cutting emissions and addressing climate change.
Available at: <http://www.sciencejournalforkids.org/ uploads/5/4/2/8/54289603/footprint_article.pdf>.
Accessed on: Dec 7th, 2017.
INSTRUCTION: Read the abstract and answer to the question.
Abstract
Scientists know greenhouse gas emissions cause climate change, but what causes greenhouse gas emissions in the first place? We assessed how many greenhouse gases are released to support the lifestyles of people living in different parts of Europe – in other words, we figured out people’s carbon footprint. We found that different lifestyle choices resulted in very different carbon footprints. In general, people with higher incomes (_____ bought more things and traveled more) had much higher carbon footprints than people ______ lived more modestly.
Understanding how our purchases affect greenhouse gas emissions is an important step to designing policies and guidelines for cutting emissions and addressing climate change.
Available at: <http://www.sciencejournalforkids.org/ uploads/5/4/2/8/54289603/footprint_article.pdf>.
Accessed on: Dec 7th, 2017.
The expression rather than means:
INSTRUCTION: Read the text and answer to the question.
Marie & Pierre Curie
• Marie Curie was a chemist and physicist famous for becoming the first person to be awarded two Nobel Prizes. She was brought up in Poland before eventually moving to France and obtaining French citizenship.
Write true (T) or false (F), according to the text.
( ) Marie Curie claimed that people should do research that is useful for humankind.
( ) Marie and Pierre Curie were both originally French.
( ) The institution founded by Marie Curie develops cancer research.
( ) Pierre Curie achievements include The Curie Point and Curie’s Law.
The correct sequence is:
INSTRUCTION: Read the text and answer to the question.
Marie & Pierre Curie
• Marie Curie was a chemist and physicist famous for becoming the first person to be awarded two Nobel Prizes. She was brought up in Poland before eventually moving to France and obtaining French citizenship.
INSTRUCTION: Read the cartoon and answer to the question.

INSTRUCTION: Read the cartoon and answer to the question.

INSTRUCTION: Read the comic strip and answer to the question.

The correct verb form to complete the sentence is:
INSTRUCTION: Read the comic strip and answer to the question.
