IGCSE Combined Science Exam: Quiz!

The correct answer is "Positive attracts negative, Positive repels positive." This is based on the principles of electrical charge. Positive charges attract negative charges because opposite charges attract each other. On the other hand, positive charges repel other positive charges because like charges repel each other.

The statement accurately describes the characteristics of transition metals. They are typically shiny, hard solids (excluding mercury), and they have a tendency to form brightly colored chemical compounds. Transition metals also tend to have high densities, high melting points, and are commonly used as catalysts. Therefore, the answer "True" is correct.

When a rod becomes negatively charged, it means that it has gained electrons. Electrons are negatively charged particles, so when the rod gains electrons, it acquires a negative charge. This is because electrons are transferred from another object to the rod, resulting in an excess of electrons on the rod's surface. Therefore, the correct answer is "gained."

Plants do indeed lose a significant amount of water through transpiration. This process helps to keep the leaves cool and also aids in the absorption of water from the roots. The statement accurately reflects the importance of water for plants and the role of transpiration in their survival.

The job of a heart valve is to prevent backflow and ensure that blood flows in one direction. It keeps the blood going forwards and ensures that it does not go backwards. This is important for the proper functioning of the heart and the circulation of blood throughout the body.

Chromatography is a technique used to separate and analyze mixtures. In this case, chlorophyll can be separated from other dyes using chromatography because it has different physical and chemical properties compared to other dyes. Chromatography involves passing a mixture through a stationary phase and a mobile phase. The different components of the mixture will move at different rates based on their affinity for the stationary phase, allowing for their separation. Therefore, chromatography is an effective method to separate chlorophyll from other dyes.

Distillation is a process used to separate a mixture of two substances based on their different boiling points. In this case, if one substance evaporates at 70 degrees and the other at 100 degrees, heating the mixture at 70 degrees will cause the substance with the lower boiling point to evaporate and collect in another beaker. Since the other substance requires a higher temperature to evaporate, it remains in its original location. This process effectively separates the two substances, demonstrating that the statement is true.

During one complete circulation of the body, blood passes through the heart two times. The first pass occurs when deoxygenated blood from the body enters the right atrium and then gets pumped to the lungs to pick up oxygen. After oxygenation, the blood returns to the heart and enters the left atrium. From there, it is pumped out to the rest of the body, completing the second pass through the heart.

In an electric circuit, current is the flow of electrons. The bigger the current, the more electrons are flowing around the circuit. The wires carry the electrons from one terminal around the circuit to the other terminal.

When the resistance in a circuit increases, it becomes more difficult for the current to flow. This is because resistance opposes the flow of electrons. As a result, the current in the circuit will slow down.

It is the other way around. Physical change is a change of state and can easily be reversed. A chemical change is when a new substance is formed and is very hard to reverse.

The given answer "Yeah, pretty much" agrees with the statement that a negatively charged object will discharge if it is touched by a conductor. It also acknowledges that often charged objects will spark when the discharge occurs.

In a series circuit, the current is the same wherever you measure it. This is because in a series circuit, the current has only one path to flow through. Therefore, the current that flows through one component of the circuit is the same as the current that flows through any other component in the circuit. This is a fundamental property of series circuits and is due to the fact that the current is conserved in a closed loop.

Bromine, iodine, and fluorine are halogens. Halogens are a group of elements in the periodic table that are highly reactive and have seven valence electrons. They are known for their ability to form salts when they react with metals. Mercury and oxygen, on the other hand, are not halogens. Mercury is a transition metal and oxygen is a nonmetal.

It's true the vein is a thin wall of muscle but it can hold low pressure, not high pressure.

This statement is true because positively charged objects have lost electrons, which results in an overall positive charge. Conversely, negatively charged objects have gained electrons, leading to an overall negative charge. Additionally, charged objects can attract uncharged or neutral objects due to the presence of electric fields.

Chromatography is a technique used to separate and analyze mixtures based on the differential solubility of its components. In this process, a mixture is dissolved in a solvent and then allowed to move through a stationary phase, such as a piece of paper. As the solvent moves, the different components of the mixture, which have varying solubilities, separate and move at different rates. The ones that dissolve well in the solvent will move up the paper more, while the ones that do not dissolve as well will stay near the bottom. This process allows for the identification and analysis of the different components in a mixture.

Not always. There are an equal amount of protons and electrons

The sum of currents is actually A1=A2+A3=A4

When a voltmeter is connected in parallel, it is connected across the component or circuit being measured. This allows the voltmeter to measure the potential difference (voltage) across the component without affecting the current flowing through it. In contrast, when a voltmeter is connected in series, it would disrupt the circuit and affect the current flow, giving inaccurate measurements. Therefore, the statement "A voltmeter is put into parallel not series" is true.

Osmosis is the movement of water molecules from an area of higher concentration (hypertonic) to an area of lower concentration (hypotonic) through a semipermeable membrane. This process aims to equalize the concentration of solutes on both sides of the membrane. Therefore, the correct answer is "high low" as it represents the movement of water from an area of higher concentration to an area of lower concentration. The other options provided are variations of the correct answer, but they all convey the same concept of osmosis.

This group of elements is known as the noble gases. They are colorless and have very low reactivity with other elements, making them ideal for creating inert atmospheres. The noble gases are located in group 0 or group 8 of the periodic table. The answer options "noble gases," "group 0," "group 8," and the numbers 0 and 8 all refer to the same group of elements with these specific traits.

The number of electrons in the outer shell is usually equal to the group number in the periodic table. This is because the group number represents the number of valence electrons, which are located in the outermost shell of an atom. Valence electrons are responsible for the chemical behavior of an element, including its ability to form bonds with other atoms. Therefore, knowing the group number can help determine the number of electrons in the outer shell.

The mass of an electron is extremely small compared to other particles. It is approximately 1/2000th the mass of a proton or a neutron. This means that electrons have a very low mass and contribute very little to the overall mass of an atom.

When you climb a high mountain, the air around you becomes less dense. As you ascend, the atmospheric pressure decreases, resulting in thinner air with fewer molecules per unit volume. This decrease in air density makes it harder to breathe because there is less oxygen available for inhalation.

It is the other way around. Metals lose electrons and Non-metals gain electrons

Surprisingly not studying for exams does not affect your coronary arteries.

Copper wire, fuse, and TV aerial are conductors because they allow the flow of electric current. Copper is an excellent conductor of electricity due to its high conductivity. Fuses are made of conductive materials that melt when there is excessive current, breaking the circuit. TV aerials are designed to receive electromagnetic signals and transmit them to the television, which requires conducting materials to work effectively. On the other hand, paper and string on a light switch are insulators as they do not allow the flow of electric current.

The given anion, (So2)4-, is incorrect. This is because the chemical formula for sulfite ion is SO32-. The subscript 4 in the given anion suggests that there are four sulfur atoms, which is not correct.

A potometer is a device used to measure the rate of transpiration in plants. It consists of a chamber that is filled with water and attached to a plant stem. As the plant transpires, water is drawn up through the stem and into the chamber, causing the water level to decrease. By measuring the rate at which the water level changes, the rate of transpiration can be determined. Therefore, a potometer is the most suitable option among the given choices as it accurately describes the device used to measure transpiration in plants.

The root hair is underground. How can it photosynthesize

The given answer lists various methods for separating mixtures. Using magnets can be used to separate mixtures containing magnetic materials. Decanting involves pouring off the liquid portion of a mixture while leaving the solid behind. Filtration involves passing a mixture through a filter to separate the solid from the liquid. Evaporation involves heating a mixture to evaporate the liquid and leave behind the solid. Distillation is a process where a mixture is heated to separate its components based on their different boiling points. Chromatography is a technique that uses a solvent to separate the components of a mixture based on their different solubilities.

The statement describes Ohm's Law, which states that the current flowing through a wire is directly proportional to the voltage across it, as long as the temperature remains constant. Ohm's Law is a fundamental principle in electrical circuits and is named after the German physicist Georg Simon Ohm. The answer options provided all refer to the same law, with variations in capitalization and article usage.

The resistance of a wire is directly proportional to its length. As the length of a wire increases, the number of collisions between the electrons and the atoms in the wire also increases, leading to a higher resistance. On the other hand, the resistance of a wire is inversely proportional to its cross-sectional area, which is determined by its thickness. A decrease in thickness results in a smaller cross-sectional area, causing the resistance to increase. Therefore, an increase in length and a decrease in thickness both contribute to an increase in the resistance of a wire.

The coronary arteries supply blood directly to the heart to give it the nutrients and oxygen it needs to respire and produce its energy. The red blood cells that carry the oxygen have a special bi-concave shape to give them a larger surface area. This allows for efficient exchange of nutrients and oxygen between the blood and the heart tissues.