Câu hỏi:
05/08/2023 1,637Part 2. Questions 66 – 75
Read the passage below and choose the best answer to each question
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.
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.
Electrical conductivity is ________.
Sách mới 2k7: 30 đề đánh giá năng lực DHQG Hà Nội, Tp. Hồ Chí Minh, BKHN 2025 mới nhất (600 trang - chỉ từ 160k).
Quảng cáo
Trả lời:
Chọn A
Câu hỏi cùng đoạn
Câu 2:
According to the passage, a metal can conduct electricity due to ________.
Lời giải của GV VietJack
Chọn C
Câu 3:
The word “outermost” in paragraph 1 mostly means ________.
Lời giải của GV VietJack
CHọn C
Câu 4:
The atoms of a metal can bond together because ________.
Lời giải của GV VietJack
Chọn D
Câu 5:
Salt in its solid state is not able to conduct electricity because ________.
Lời giải của GV VietJack
Chọn D
Câu 6:
The word “they” in paragraph 3 refers to ________.
Lời giải của GV VietJack
Chọn D
Câu 7:
Water is a poor conductor because it contains ________.
Lời giải của GV VietJack
Chọn B
Câu 8:
We can have problems when touching electrical devices with wet hands because ________.
Lời giải của GV VietJack
Chọn B
Câu 9:
Which of the following is NOT true according to the passage?
Lời giải của GV VietJack
Chọn A
Câu 10:
Which of the following could best serve as the title of the passage?
Lời giải của GV VietJack
Chọn A
Đã bán 152
Đã bán 114
Đã bán 132
Đã bán 47
CÂU HỎI HOT CÙNG CHỦ ĐỀ
Câu 1:
SECTION I: LISTENING(You will hear twice for each part)
Part 1. You will hear a doctor talking about how people can lead a healthier life. For each question, put a tick in the correct box.
To become healthier you should _______.
Câu 2:
về câu hỏi!