Dịch:ko dùng google dịch vì hay bị sai -A mixture contains different subtances that are not chemically joined to each other. -Pure subtances are composed of only one kind of molecule in it.Most o...

#Tiếng anh lớp 6

2

D

dương

30 tháng 11 2017

Một hỗn hợp có chứa các phụ khác nhau mà không liên quan hóa học với nhau.

-Pure subtances chỉ bao gồm một loại phân tử trong đó.Hầu hết những thứ trong thế giới này là hỗn hợp.

-Một hỗn hợp có thể được tách biệt về thể chất hoặc vật lý.

- Khi một hỗn hợp muối và nước được cách nhau bằng cách sưởi ấm, có thể thu được nước tinh khiết.

1.Bạn có thể tách riêng một hỗn hợp nước và cát?

2. Bạn có thể làm gì để tách sắt và muối

D

dương

30 tháng 11 2017

xin lỗi nhé mink ko giỏi thí nghiệm

X Read the passage. Answer the questions below. Scientists have discovered that the ozone layer is getting thinner. Some predict that the sun’s rays will cause a sharp increase in deaths from skin cancer over the next fifty years. These harmful rays can also damage the eyes, create wrinkles, and cause other health problems. The stratosphere contains a form of oxygen called ozone. Ozone is a molecule composed of three oxygen atoms. The chemical formula of ozone is 03. Oxygen molecules make...

TT

Trương Thu Hoa

3 tháng 2 2020

#Tiếng anh lớp 8

1

NH

Nguyễn Huyền Trâm

3 tháng 2 2020

X Read the passage. Answer the questions below.

Scientists have discovered that the ozone layer is getting thinner. Some predict that the sun’s rays will cause a sharp increase in deaths from skin cancer over the next fifty years. These harmful rays can also damage the eyes, create wrinkles, and cause other health problems.

The stratosphere contains a form of oxygen called ozone. Ozone is a molecule composed of three oxygen atoms. The chemical formula of ozone is 03. Oxygen molecules make up about 21% of all gases in the Earth’s atmosphere. They consist of two atoms of oxygen and are labeled 02. Most ozone found in our atmosphere is formed by an interaction between oxygen molecules and ultraviolet radiation (UV) from the sun. When ultraviolet radiation hits an oxygen molecule, it may cause the molecule to break apart into single atoms of oxygen. These single atoms are very reactive, and a single oxygen atom can combine with a molecule of oxygen to form ozone.

1.What do people say about the rate of deaths from skin cancer in the future?

=> Some predict that the sun’s rays will cause a sharp increase in deaths from skin cancer over the next fifty years. These harmful rays can also damage the eyes, create wrinkles, and cause other health problems.

2. How many oxygen atoms are there in a molecule?

=> Oxygen molecules make up about 21% of all gases in the Earth’s atmosphere

3.What elements participate in the formation process of ozone?

=> Most ozone found in our atmosphere is formed by an interaction between oxygen molecules and ultraviolet radiation (UV) from the sun.

4.What happens when an oxygen molecule and an ultraviolet radiation hit each other?

=> When ultraviolet radiation hits an oxygen molecule, it may cause the molecule to break apart into single atoms of oxygen

5.What is the feature of single atoms?

=> These single atoms are very reactive, and a single oxygen atom can combine with a molecule of oxygen to form ozone.

TT

Trương Thu Hoa

3 tháng 2 2020

cảm ơn ạ!

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions The ability to conduct electricity is one of the key properties of a metal. Other solid material such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved in water. The ability of metals to...

LQ

Lê Quỳnh Anh

29 tháng 5 2019

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions

The ability to conduct electricity is one of the key properties of a metal. Other solid material such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved in water. The ability of metals to conduct electricity is due to how their atoms bond together. In order to bond together the metal atoms lose at least one of their outermost electrons. This leaves the metal atoms with a positive charge and they are now strictly ions. The lost electrons are free to move in what are known as a sea of electrons. Since the electrons are negatively charged they attract the ions and this is what keeps the structure together.

An electric current is a flow of charge and since the electrons in the sea of electrons are free to move they can be made to flow in one direction when a source of electrical energy such as a battery is connected to the metal. Hence we have an electric current flowing through the wire, and this is what makes metals such good conductors of electricity. The only other common solid conducting material that pencil users are likely to encounter is graphite (what the ‘lead’ of a pencil is made from). Graphite is a form of carbon and again the carbon atoms bond in such a way that there is a sea of electrons that can be made to flow as an electric current. Likewise, if we have an ionic substance like salt we can make the electrically charged ions flow to create a current but only when those ions are free to move, either when the substance is a liquid or dissolved in water. In its solid state an ionic substance like salt cannot conduct electricity as its charged ions cannot flow. Freshwater Aquarium Fish

Playlist Freshwater Aquarium Fish

Electrical insulators are substances that cannot conduct electricity well either, because they contain no charged particles or any charged particles they might contain do not flow easily. Water itself is a poor conductor or electricity as it does not contain a significant amount of fully charged particles (the ends of a water molecule are partly charged but overall the molecule is neutral). However, most water we encounter does contain dissolved charged particles, so it will be more conductive than pure water. Many of the problems that occur when touching electrical devices with wet hands result from the ever-present salt that is left on our skin through perspiration and it dissolves in the water to make it more conductive.

By Helena Gillespie and Rob Gillespie. Science for Primary School Teacher. OUP

Water is a poor conductor because it contains

A. no positive or negative electric charge

B. only a small amount of fully charged particles

C. only a positive electric charge

D. only a negative electric charge

1

DH

Dương Hoàn Anh

29 tháng 5 2019

Đáp án : B

Câu 2 đoạn cuối: Water itself is a poor conductor or electricity as it does not contain a significant amount of fully charged particles (không chứa đủ lượng hạt mang điện cần thiết)

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42The ability to conduct electricity is one of the key properties of a metal. Other solid materials such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved in water. The ability of metals to conduct electricity is due to how...

LQ

Lê Quỳnh Anh

7 tháng 7 2019

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42

The ability to conduct electricity is one of the key properties of a metal. Other solid materials such as silicon can conduct electricity but only effectively at certain temperatures. Also, some substances such as salt (sodium chloride) can conduct when molten or when dissolved in water. The ability of metals to conduct electricity is due to how their atoms bond together. In order to bond together the metal atoms lose at least one of their outermost electrons. This leaves the metal atoms with a positive charge and they are now strictly ions. The lost electrons are free to move in what is known as a sea of electrons. Since the electrons are negatively charged they attract the ions and this is what keeps the structure together.

An electric current is a flow of charge and since the electrons in the sea of electrons are free to move they can be made to flow in one direction when a source of electrical energy such as a battery is connected to the metal. Hence we have an electric current flowing through the wire, and this is what makes metals such good conductors of electricity. The only other common solid conducting material that pencil users are likely to encounter is graphite (what the „lead’ of a pencil is made from). Graphite is a form of carbon and again the carbon atoms bond in such a way that there is a sea of electrons that can be made to flow as an electric current. Likewise, if we have an ionic substance like salt we can make the electrically charged ions flow to create a current but only when those ions are free to move, either when the substance is a liquid or dissolved in water. In its solid state an ionic substance like salt cannot conduct electricity as its charged ions cannot flow.

Electrical insulators are substances that cannot conduct electricity well either, because they contain no charged particles or any charged particles they might contain do not flow easily. Water itself is a poor conductor of electricity as it does not contain a significant amount of fully charged particles (the ends of a water molecule are partly charged but overall the molecule is neutral). However, most water we encounter does contain dissolved charged particles, so it will be more conductive than pure water. Many of the problems that occur when touching electrical devices with wet hands result from the ever-present salt that is left on our skin through perspiration and it dissolves in the water to make it more conductive.

By Helena Gillespie and Rob Gillespie. Science for Primary School Teachers. OUP

Water is a poor conductor because it contains ______.

A. only a positive electric charge

B. only a small amount of fully charged particles

C. only a negative electric charge

D. no positive or negative electric

1

DH

Dương Hoàn Anh

7 tháng 7 2019

Đáp án B

Nước là chất dẫn điện kém bởi vì nó chứa

A.chỉ có điện tích dương

B. chỉ một lượng nhỏ các phân tử mang đầy điện

C. chỉ mang điện tích âm

D. không có điện tích âm hay điện tích dương

Dẫn chứng:Water itself is a poor conductor of electricity as it does not contain a significant amount of fully charged particles (the ends of a water molecule are partly charged but overall the molecule is neutral).

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions. Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book "The Natural History of Selboure" (1786), the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover's nest, and how the mother laid another egg each day to make up for...

LQ

Lê Quỳnh Anh

21 tháng 10 2018

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions.

Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book "The Natural History of Selboure" (1786), the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover's nest, and how the mother laid another egg each day to make up for the missing one. He noted that other species of birds ignore the absence of a single egg but abandon their nest if more than one egg has been removed. It has also been noted by naturalists that a certain type of wasp always provides five - never four, never six - caterpillars for each of their eggs so that their young have something to eat when the eggs hatch. Research has also shown that both mice and pigeons can be taught to distinguish between odd and even numbers of food pieces.

These and similar accounts have led some people to infer that creatures other than humans can actually count. They also point to dogs that have been taught to respond to numerical questions with the correct number of banks, or to horses that seem to solve arithmetic problems by stomping their hooves the proper number of times.

Animals respond to quantities only when they are connected to survival as a species - as in the case of the eggs - or survival as individuals - as in the case of food. There is no transfer to other situations of from concrete reality to the abstract notion of numbers. Animals can "count" only when the objects are present and only when the numbers involved are small - not more than seven or eight. In lab experiments, animals trained to "count" one kind of object were unable to count any other type. The object, not the numbers, are what interest them. Animals' admittedly remarkable achievements simply do not amount to evidence of counting, nor do they reveal more than innate instincts, refined by the genes of successive generations, or the results of clever, careful conditioning by trainers.

The word "surreptitiously" is closest in meaning to ________.

A. stubbornly

B. secretly

C. quickly

D. occasionally

1

DH

Dương Hoàn Anh

21 tháng 10 2018

Đáp án B.

Key words: surreptitiously, closest in meaning.

A. stubbornly: cứng đầu

B. secretly: bí mật, kín đáo, giấu giếm

C. quickly: nhanh chóng

D. occasionally: thỉnh thoảng

- surreptitiously: lén lút, gian lận, lừa dối.

Vậy đáp án chính xác là đáp án B.

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book “ The natural History of Selboure ” (1786 ) , the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover’s nest , and how the mother laid another egg each day to...

LQ

Lê Quỳnh Anh

29 tháng 12 2018

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book “ The natural History of Selboure ” (1786 ) , the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover’s nest , and how the mother laid another egg each day to make up for the missing one . He noted that other species of birds ignore the absence of a single egg but abandon their nests if more than one egg has been removed. It has also been noted by naturalists that a certain type of wasp always provides five – never four, never six - caterpillars for each of their eggs so that their young have something to eat when the eggs hatch . Research has also shown that both mice and pigeons can be taught to distinguish between odd and even numbers of food pieces.

These and similar accounts have led some people to infer that creatures other than humans can actually count. They also point to dogs that have been taught to respond to numerical questions with the correct number of barks, or to horses that seem to solve arithmetic problems by stomping their hooves the proper number of times.

Animals respond to quantities only when they are connected to survival as a species – as in the case of the eggs – or survival as individuals - as in the case of food. There is no transfer to other situations or from concrete reality to the abstract notion of numbers. Animals can “count” only when the objects are present and only when the numbers involved are small – not more than seven or eight. In lab experiments, animals trained to “count” one kind of object were unable to count any other type. The objects, not the numbers, are what interest them. Animals admittedly remarkable achievements simply do not amount to evidence of counting, nor do they reveal more than innate instincts, refined by the genes of successive generations, or the results of clever, careful conditioning by trainers .

The word “accounts” is closest in meaning to

A. reasons

B. reports

C. deceptions

D. invoices

1

DH

Dương Hoàn Anh

29 tháng 12 2018

Đáp án B

“accounts” = reports: báo cáo, tường trình, thuật lại, kể lại

Reasons: lý do

Deceptions: sự dối trá. Lừa gạt

Invoices: hoá đơn

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book “The Natural History of Selboure” (1786), the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover’s nest, and how the mother laid another egg each day to make up...

LQ

Lê Quỳnh Anh

24 tháng 6 2017

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book “The Natural History of Selboure” (1786), the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover’s nest, and how the mother laid another egg each day to make up for the missing one. He noted that other species of birds ignore the absence of a single egg but abandon their nests if more than one egg has been removed. It has also been noted by naturalists that a certain type of wasp always provides five - never four, never six -caterpillars for each of their eggs so that their young have something to eat when the eggs hatch. Research has also shown that both mice and pigeons can be taught to distinguish between odd and even numbers of food pieces.

These and similar accounts have led some people to infer that creatures other than humans can actually count. They also point to dogs that have been taught to respond to numerical questions with the correct number of barks, or to horses that seem to solve arithmetic problems by stomping their hooves the proper number of times.

Animals respond to quantities only when they are connected to survival as a species - as in the case of the eggs - or survival as individuals - as in the case of food. There is no transfer to other situations or from concrete reality to the abstract notion of numbers. Animals can “count” only when the objects are present and only when the numbers involved are small - not more than seven or eight. In lab experiments, animals trained to “count” one kind of object were unable to count any other type. The objects, not the numbers, are what interest them. Animals’ admittedly remarkable achievements simply do not amount to evidence of counting, nor do they reveal more than innate instincts, refined by the genes of successive generations, or the results of clever, careful conditioning by trainers.

The word “surreptitiously” is closest in meaning to _______.

A. stubbornly

B. secretly

C. quickly

D. occasionally

1

DH

Dương Hoàn Anh

24 tháng 6 2017

Đáp án B.

Key words: surreptitiously, closest in meaning.

A. stubbornly: cứng đầu

B. secretly: bí mật, kín đáo, giấu giếm

C. quickly: nhanh chóng

D. occasionally: thỉnh thoảng

- surreptitiously: lén lút, gian lận, lừa đối

Vậy đáp án chính xác là đáp án B.

MEMORIZE

- stubbornly (adv): cứng đầu

- stubborn (adj)

as stubborn as a mule: cứng đầu cứng cổ, ương bướng

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book “The Natural History of Selboure” (1786), the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover’s nest, and how the mother laid another egg each day to make up...

DM

Dương Minh

23 tháng 12 2019

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book “The Natural History of Selboure” (1786), the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover’s nest, and how the mother laid another egg each day to make up for the missing one. He noted that other species of birds ignore the absence of a single egg but abandon their nests if more than one egg has been removed. It has also been noted by naturalists that a certain type of wasp always provides five - never four, never six -caterpillars for each of their eggs so that their young have something to eat when the eggs hatch. Research has also shown that both mice and pigeons can be taught to distinguish between odd and even numbers of food pieces.

These and similar accounts have led some people to infer that creatures other than humans can actually count. They also point to dogs that have been taught to respond to numerical questions with the correct number of barks, or to horses that seem to solve arithmetic problems by stomping their hooves the proper number of times.

Animals respond to quantities only when they are connected to survival as a species - as in the case of the eggs - or survival as individuals - as in the case of food. There is no transfer to other situations or from concrete reality to the abstract notion of numbers. Animals can “count” only when the objects are present and only when the numbers involved are small - not more than seven or eight. In lab experiments, animals trained to “count” one kind of object were unable to count any other type. The objects, not the numbers, are what interest them. Animals’ admittedly remarkable achievements simply do not amount to evidence of counting, nor do they reveal more than innate instincts, refined by the genes of successive generations, or the results of clever, careful conditioning by trainers.

The word “surreptitiously” is closest in meaning to _______.

A. stubbornly

B. secretly

C. quickly

D. occasionally

1

NH

Nguyen Hoang Hai

23 tháng 12 2019

Đáp án B.

Key words: surreptitiously, closest in meaning.

A. stubbornly: cứng đầu

B. secretly: bí mật, kín đáo, giấu giếm

C. quickly: nhanh chóng

D. occasionally: thỉnh thoảng

- surreptitiously: lén lút, gian lận, lừa đối

Vậy đáp án chính xác là đáp án B.

MEMORIZE

- stubbornly (adv): cứng đầu

- stubborn (adj)

as stubborn as a mule: cứng đầu cứng cổ, ương bướng

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book “The Natural History of Selboure” (1786), the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover’s nest, and how the mother laid another egg each day to make up...

DM

Dương Minh

9 tháng 1 2019

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book “The Natural History of Selboure” (1786), the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover’s nest, and how the mother laid another egg each day to make up for the missing one. He noted that other species of birds ignore the absence of a single egg but abandon their nests if more than one egg has been removed. It has also been noted by naturalists that a certain type of wasp always provides five - never four, never six -caterpillars for each of their eggs so that their young have something to eat when the eggs hatch. Research has also shown that both mice and pigeons can be taught to distinguish between odd and even numbers of food pieces.

These and similar accounts have led some people to infer that creatures other than humans can actually count. They also point to dogs that have been taught to respond to numerical questions with the correct number of barks, or to horses that seem to solve arithmetic problems by stomping their hooves the proper number of times.

Animals respond to quantities only when they are connected to survival as a species - as in the case of the eggs - or survival as individuals - as in the case of food. There is no transfer to other situations or from concrete reality to the abstract notion of numbers. Animals can “count” only when the objects are present and only when the numbers involved are small - not more than seven or eight. In lab experiments, animals trained to “count” one kind of object were unable to count any other type. The objects, not the numbers, are what interest them. Animals’ admittedly remarkable achievements simply do not amount to evidence of counting, nor do they reveal more than innate instincts, refined by the genes of successive generations, or the results of clever, careful conditioning by trainers.

The word “surreptitiously” is closest in meaning to _______.

A. stubbornly

B. secretly

C. quickly

D. occasionally

1

NH

Nguyen Hoang Hai

9 tháng 1 2019

Đáp án B.

Key words: surreptitiously, closest in meaning.

A. stubbornly: cứng đầu

B. secretly: bí mật, kín đáo, giấu giếm

C. quickly: nhanh chóng

D. occasionally: thỉnh thoảng

- surreptitiously: lén lút, gian lận, lừa đối

Vậy đáp án chính xác là đáp án B.

MEMORIZE

- stubbornly (adv): cứng đầu

- stubborn (adj)

as stubborn as a mule: cứng đầu cứng cổ, ương bướng

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book “ The natural History of Selboure ” (1786 ) , the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover’s nest , and how the mother laid another egg each day to...

LQ

Lê Quỳnh Anh

31 tháng 12 2019

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Animals have an intuitive awareness of quantities. They know without analysis the difference between a number of objects and a smaller number. In his book “ The natural History of Selboure ” (1786 ) , the naturalist Gilbert White tells how he surreptitiously removed one egg a day from a plover’s nest , and how the mother laid another egg each day to make up for the missing one . He noted that other species of birds ignore the absence of a single egg but abandon their nests if more than one egg has been removed. It has also been noted by naturalists that a certain type of wasp always provides five – never four, never six - caterpillars for each of their eggs so that their young have something to eat when the eggs hatch . Research has also shown that both mice and pigeons can be taught to distinguish between odd and even numbers of food pieces.

These and similar accounts have led some people to infer that creatures other than humans can actually count. They also point to dogs that have been taught to respond to numerical questions with the correct number of barks, or to horses that seem to solve arithmetic problems by stomping their hooves the proper number of times.

Animals respond to quantities only when they are connected to survival as a species – as in the case of the eggs – or survival as individuals - as in the case of food. There is no transfer to other situations or from concrete reality to the abstract notion of numbers. Animals can “count” only when the objects are present and only when the numbers involved are small – not more than seven or eight. In lab experiments, animals trained to “count” one kind of object were unable to count any other type. The objects, not the numbers, are what interest them. Animals admittedly remarkable achievements simply do not amount to evidence of counting, nor do they reveal more than innate instincts, refined by the genes of successive generations, or the results of clever, careful conditioning by trainers .

The word “surreptitiously” is closest in meaning to

A. quickly

B. occasionally

C. stubbornly

D. secretly

1

DH

Dương Hoàn Anh

31 tháng 12 2019

Đáp án D

“surreptitiously”= secretly: lén lút, vụng trộm, một cách bí mật

Quickly: nhanh chóng

Occasionally: thỉnh thoảng

Stubbornly: một cách cứng đầu