O ________________, fórmula molecular ________, é um ________ utilizado no tratamento de água. Ao ser adicionado à água em meio ________, forma flocos, que se juntam a impurezas sólidas presentes na água, constituindo estruturas maiores, que precipitam. O processo mencionado é denominado de ________________.
Assinale a alternativa que preenche, correta e respectivamente, as lacunas do trecho acima. 

A reação de neutralização do hidróxido de sódio com ácido clorídrico é expressa pela equação:

HCℓ + NaOH → NaCℓ + H₂O

Determine o volume de HCℓ, na concentração 0,05 mol∙L^-1, necessário para neutralizar 10 mL de solução 0,1 mol∙L^-1 de NaOH. Dados: Cℓ = 35,5 g∙mol^-1; Na = 23 g∙mol^-1; O = 16 g∙mol^-1; H = 1 g∙mol^-1.

O cloreto de bário, de fórmula química BaCl₂, é uma substância muito utilizada no setor de metalurgia em sais de têmpera, com a finalidade de aumentar a dureza de ferro-ligas e/ou aços (tratamento térmico de metais). É utilizado também em indústrias de sais de bário e em indústrias para eliminação de sulfato. Determine a massa de cloreto de bário, em gramas, necessária para preparar 500 mL de solução de concentração 0,5 mol∙L^-1. Dados: Massas moleculares: Ba = 137 g/mol e Cℓ = 35,5 g/mol.

O álcool etílico, também chamado de etanol, é o álcool presente nas bebidas alcoólicas. Considere para cada copo de 120 mL de uma determinada marca de cachaça a presença de 45,8 mL de álcool etílico e determine a graduação alcoólica dessa bebida, calculando a porcentagem em volume.

Observe as moléculas a seguir e analise as assertivas abaixo:
  
I. O butano apresenta ponto de ebulição mais elevado do que o 2-metilpropano.
II. O 2-metilpropano e o butano são hidrocarbonetos com fórmula molecular C4H10.
III. O 2-metilpropano é uma molécula polar enquanto o butano é uma molécula apolar. 

 Quais estão corretas?

O produto principal da reação de nitração do propano com ácido nítrico é:

O ácido acetilsalicílico ou AAS, conhecido popularmente como aspirina, nome de uma marca que se tornou de uso comum, é um fármaco da família dos salicilatos. Considerando a sua fórmula abaixo, assinale a alternativa correta. 
  

Analyse the following sentences:

I. Two miles aren’t very far to walk.

II. Italy are playing Brazil next Sunday.

III. The government have decided to increase taxes.

Considering the nouns are plural or singular, which ones are correct?

Analyse the following sentences:

_____ Earth goes round ______ sun.

There’s ______ lift on his building, so he doesn’t mind living on _______ tenth floor.

There are millions of stars in ________ space.

Mark the alternative that correctly and respectively fills the blancks:

Consider the situation below and analyze the following sentences:

Sarah has a daughter. Her name is Martha, and she is ten years old. Every day she goes to school. She stays there from 9 a.m. to 3 p.m. She’s at school now. Today Martha’s mother wants to speak to her daughter’s teacher. So she has gone to the school to see her. She’s at the school now.

I. We say Martha “goes to school” and “is at school” because we are not thinking of a specific school.

II. We say Martha’s mother “has gone to the school” and “is at the school” because we refer to a specific building (Martha’s school).

III. We say Martha’s mother “has gone to the school” and “is at the school” because we refer to one of many schools (Martha’s school).

Which ones are correct?

Analyze the following sentences:

I. They’re in the kitchen making coffee.

II. Having found a hotel, we looked for somewhere to eat.

III. Feeling tired, I went to bed early.

Which of the following alternatives is correct?

Consider the following situation:

Last week I saw a friend of mine at the bus stop on my way home. She was waiting for the bus. So, I can say:

Consider the following situation and mark the correct alternative.

This morning my father got up at 7 a.m., had a shower, had breakfast and afterwards went to work. More precisely at 8:30 a.m. he got into the car and drove off. I saw it. So, I can say:

Analyze the following sentences:

Please, be ______ time. Don’t be late.

I intend to be home _____ time for dinner.

They’re going away _____ the end of January.

The 8:00 train arrived ______ time.

At first we didn’t get along, but ____ the end we became good friends.

Mark the alternative that correctly and respectively fills the blancks:

In which of the following sentences is the bold word “traveling” the object of the verb?

Consider the following situation:

“Last summer Paul and Sarah went on vacation to the beach. It rained a lot, but they had a good time.”

Choose the alternative that CAN’T be replaced with “... but they had a good time”:

Analyze the following sentences:

I. If I have time I will visit my parents next weekend.

II. If I had time I would visit my parents every weekend.

III. If I had had time I would have visited my parentes last weekend.

Which of the following alternatives is correct?

In which of the sentences “have to” isn’t usually replaced with “must”? Choose the correct option.

In the sentence “I was so tired I could sleep for twenty hours” what the speaker infers is that:

Analyze the following statements about the sentence “I _______ come and see you tomorrow”:

I. If we fill in the gap with “can” it means something is possible or somebody has the ability to do it.

II. If we fill in the gap with “may” it means there’s a probability of something to happen.

III. If we fill in the gap with “should” it means it is a good or the right thing to do.

Which one are correct?