Science Quiz For Grade 7

The voltage applied to a resistor can be calculated using Ohm's Law, which states that voltage is equal to the current multiplied by the resistance. In this case, the current is given as 4 Amperes and the resistance is 10 Ohms. Therefore, the voltage applied to the resistor is 4 Amperes multiplied by 10 Ohms, which equals 40 Volts.

The explanation for the given correct answer is that atoms are the fundamental particles that make up matter. Atoms consist of electrons, protons, and neutrons. Electrons are negatively charged particles that orbit around the nucleus of an atom. Protons are positively charged particles found in the nucleus, and neutrons are neutral particles also found in the nucleus. Therefore, atoms are the building blocks of matter, and they are composed of electrons, protons, and neutrons.

The correct answer is "مصدر طاقة وحمل وأسلاك" because a circuit requires a power source to provide the energy, a load to consume the energy, and wires to connect the components and allow the flow of electricity. Without any of these three components, a circuit cannot function properly.

The correct answer is "الكشاف الكهربائي" (Electric tester). An electric tester is used to determine whether an object is charged or not. It is a device that can detect the presence of an electric current by measuring voltage or continuity. By using an electric tester, one can safely check if an object or electrical circuit is carrying an electrical charge before working on it.

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The correct answer is قابلية التفاعل (reactivity). This refers to the ability of a substance to undergo chemical reactions with other substances. It indicates the likelihood of a substance to participate in chemical reactions and form new compounds. Reactivity is an important property in chemistry as it helps in understanding how substances interact with each other and how they can be used in various chemical processes.

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The correct answer is "الغاز يمكن ان يضغط" which translates to "Gas can be compressed". This answer is supported by the previous statements in the question. The question mentions that the size of the gas is constant and the gas can be compressed. This implies that the gas can be squeezed or compressed into a smaller volume, allowing for different shapes of the balloon.

The correct answer is "البروتونات". Protons are positively charged particles found in the nucleus of an atom. Electrons, on the other hand, carry a negative charge and are located in the electron cloud surrounding the nucleus. Neutrons have no charge and are also found in the nucleus. Therefore, out of the given options, only protons have a positive charge.

شدة التيار الكهربائي تعتمد على المقاومة وفرق الجهد. المقاومة تحدد مقدار تدفق التيار في الدائرة، حيث تكون كمية المقاومة أكبر كلما كان التيار أقل. أما فرق الجهد، فهو الفرق في القوة الدافعة للتيار بين نقطتين في الدائرة، حيث يكون التيار أكبر كلما كان فرق الجهد أعلى. لذا، يتأثر شدة التيار بكلا المقاومة وفرق الجهد.

At high temperatures, the particles have more kinetic energy, which causes them to move faster. This is because the increase in temperature leads to an increase in the average kinetic energy of the particles. Therefore, the correct answer is that the particles move at a higher speed.

The power of a device can be calculated using the formula P = VI, where P is power, V is voltage, and I is current. In this question, the current is given as 0.5 Amps and the voltage is given as 220 volts. Plugging these values into the formula, we get P = (0.5)(220) = 110 Watts. Therefore, the correct answer is 110.

A magnetic field is produced by an electric current flowing through a wire. This phenomenon is described by Ampere's law, which states that a magnetic field is created around a current-carrying wire. The magnetic field produced can be detected and measured using a compass. Therefore, the correct answer is "مجال مغنطيسي" (magnetic field).

When a solid object with a lower density than water is placed in water, it floats. This is because the buoyant force acting on the object is greater than its weight, causing it to rise to the surface and remain there. The buoyant force is generated by the displaced water, which exerts an upward force on the object. As a result, the object does not sink but instead floats on the surface of the water.

The explanation for the given correct answer is that when the mass of an object is large, its inertia or resistance to change in motion is also large. This means that it requires more force to accelerate or decelerate the object. Therefore, the self-inductance or self-inductive property of the object is large, resulting in a large value for its self-inductance.

The correct answer is "التوصيل" because it refers to the process of transferring electrons from one body to another through direct contact, such as in the case of conducting materials or electrical circuits. "الدلك" means rubbing or massaging, and "الحث" means induction, which are not directly related to the transfer of electrons through direct contact.

The answer "جيدة التوصيل للحرارة" (good thermal conductivity) is correct because transitional metals have high thermal conductivity due to the presence of free electrons that can easily transfer heat energy. This property makes them efficient in conducting heat and is one of the reasons why they are used in industries such as aluminum production. However, they are poor conductors of electricity because their valence electrons are not easily available for electrical conduction.

Each column in the periodic table is called a "group" or "family". These groups contain elements with similar chemical properties and valence electron configurations. The elements within a group have the same number of valence electrons, which determines their reactivity and chemical behavior. Therefore, the correct answer is "مجموعة" which translates to "group" in English.

التغير في الحالة من الصلبة إلى السائلة يسمى الانصهار.

The correct answer is "الذي يستقر في القاع" because when multiple liquids that do not mix are poured together, the liquid with the highest density will settle at the bottom. This is because density is a measure of how compact the particles in a substance are, and denser liquids have more particles packed closely together, causing them to sink to the bottom.

The correct answer "طارد للحرارة" translates to "heat repellent" in English. This means that the substance described in the question is able to repel or resist heat, resulting in a decrease in its temperature or energy.

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The correct answer is "يخفض فرق الجهد ويرفع التيار" which translates to "It reduces the voltage and increases the current." This means that a step-down transformer decreases the voltage while increasing the current. This is because the primary coil has more turns than the secondary coil, causing the voltage to decrease, but the current to increase according to the principle of conservation of energy.

The correct answer is "فلزات" (metals). This is because the question is asking about the majority of elements in the periodic table, and metals make up the largest group of elements in the table. Metals are known for their ability to conduct heat and electricity, as well as their luster and malleability.

The atomic mass of an atom is determined by the number of protons and neutrons in its nucleus. In this case, the atom is composed of 79 protons and 118 neutrons, which gives a total of 197 nucleons (protons + neutrons). Therefore, the atomic mass of this atom is 197.

Grinding wheat does not involve a chemical change. It is a physical process where the wheat is broken down into smaller pieces without any change in its chemical composition. Rusting of metal and digestion of food, on the other hand, are examples of chemical changes where the substances involved undergo a transformation at the molecular level.

The correct answer is "المغانط الحديدية والمغانط الكهربائية" which translates to "Iron magnets and electric magnets" in English. This answer is correct because iron magnets and electric magnets are two types of magnets. Iron magnets are permanent magnets made of iron or steel, while electric magnets are temporary magnets created by passing an electric current through a coil of wire. Both types of magnets have magnetic properties and can attract or repel other magnetic materials.

انفجار الأسهم النارية ليس مثالًا على التغير الفيزيائي لأنه ينتج عن تفاعل كيميائي وليس تغيرًا في حالة المادة. في حالة انفجار الأسهم النارية، يحدث تفاعل كيميائي سريع يؤدي إلى تحويل المواد الكيميائية الموجودة في الأسهم إلى غازات تتميز بزيادة حجمها وارتفاع درجة حرارتها وانفجارها بشكل عنيف. هذا التغير ليس فيزيائيًا لأنه ينتج عن تفاعلات كيميائية وليس تغيرًا في الشكل أو الحالة الفيزيائية للمادة.

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The correct answer is "الجرس الكهربائي" (Electric Bell). An electric bell is an application of an electromagnet. When an electric current flows through the coil of the electromagnet, it creates a magnetic field that attracts a metal armature, causing the bell to ring. This demonstrates the principle of electromagnetism, where electricity and magnetism are interrelated.

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The correct answer is "يتغير بتغير المكان" which translates to "changes with a change in location." This is because weight is a force that depends on the gravitational pull acting on an object, and the strength of gravity can vary depending on the location. Mass, on the other hand, is a measure of the amount of matter in an object and remains constant regardless of its location.

The correct answer is "القدرة الكهربائية". This is because the question is asking for the rate of change of electrical energy into other forms in a unit of time, which is defined as power. Power is measured in watts and represents the rate at which work is done or energy is transferred. Therefore, the correct answer is "القدرة الكهربائية".

عندما نمزج ملعقة ملح مع كوب ماء، يحدث عملية الذوبان حيث يتفكك الصوديوم والكلوريد في جزيئاتها الفردية وتتشتت في الماء. وبما أن الماء هو المادة التي تقوم بذوبان الملح فيها، فإن الماء هو المذيب في هذا السياق.

ترشيح هو عملية فصل المواد الصلبة عن السائلة باستخدام وسيلة تسمى الفلتر. يتم تمرير المزيج من المواد الصلبة والسائلة من خلال فلتر يسمح بمرور السائلة ويمنع مرور المواد الصلبة. وبالتالي، فإن الترشيح لا يفكك المركبات، بل يقوم بفصلها عن بعضها البعض بناءً على حجمها أو خواصها الفيزيائية.

The correct answer is "تيار متناوب" (alternating current). This is because the question states that the electric current continuously changes its direction of flow, which is a characteristic of alternating current. Direct current (تيار مستمر) flows in only one direction, while the term "تيار ثابت" (constant current) is not commonly used in electrical terminology.

The given question is asking for the meaning of the number of protons in the nucleus of an atom. The correct answer is "العدد الذري" which translates to "atomic number" in English. The atomic number represents the number of protons in the nucleus of an atom and determines the element's identity. It is a unique characteristic of each element and helps in organizing the periodic table.

The correct answer suggests that elements combine to form compounds in specific mass ratios. This means that the elements come together in fixed proportions based on their atomic masses. This concept is known as the law of definite proportions, which states that a compound always contains the same elements in the same ratio by mass. This explanation aligns with the given answer choice "بنسب كتلية معينة" which translates to "in specific mass ratios."

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The correct answer is "خصائص المغنطيس" which translates to "magnetic properties" in English. This answer is supported by the context of the question which mentions "القطبان والقوى المغنطيسية والمجالات المغنطيسية" meaning "poles, magnetic forces, and magnetic fields" which are all characteristics or properties of magnets. Therefore, the correct answer is "خصائص المغنطيس" or "magnetic properties".

The word "دوري" in Arabic means "periodic" or "cyclic". It is used to describe something that happens at regular intervals or in a recurring manner. In this context, the correct answer "في فترات منتظمة" means "at regular intervals" and accurately describes the nature of the event or action being referred to.

The electron has the lowest mass among the given options. Electrons are subatomic particles that orbit around the nucleus of an atom. They have a very small mass compared to protons and neutrons. Protons and neutrons, on the other hand, are found in the nucleus and have much larger masses than electrons. Therefore, the electron has the lowest mass out of the three options.

المجال المغنطيسي الناتج عن تيار في ملف لولبي يتم تعزيزه بزيادة شدة التيار وزيادة عدد لفات الملف. وبالتالي، كل ما سبق هو الإجابة الصحيحة.

A solid solution of a metal or non-metal dissolved in a metal is called a "سبيكة" (spike). This term refers to the mixture of two or more elements, where one element is a metal and the other element can be a metal or a non-metal. In this case, the solid solution is formed when the metal or non-metal is dissolved in the solid metal.

When the resistance increases and the voltage difference remains constant, the current decreases. This is because according to Ohm's Law, the current is inversely proportional to the resistance. Therefore, as the resistance increases, the current flowing through the circuit decreases.

The correct answer states that an electric current is produced when the electric field changes. This is because a changing electric field induces a magnetic field, and the interaction between the two fields results in the generation of an electric current.

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There is only one path for the charges to flow in a series circuit. In a series circuit, the components are connected one after another, so the charges have to pass through each component in order. Therefore, there is no alternative path for the charges to take.

The best indicator to determine if a chemical change has occurred is when the components of a substance change. This means that the chemical composition of the substance has been altered, indicating a chemical reaction has taken place. Changes in the state of matter or separation into layers may not necessarily indicate a chemical change, as these can occur in physical changes as well. Therefore, the most reliable indicator of a chemical change is the alteration of the substance's components.