Year 7 Science Semester Two

Air pressure is defined as the amount of "push" of air particles on a set area of space. To measure air pressure accurately, a device called a barometer is used. A barometer works by measuring the atmospheric pressure exerted by the weight of the air above it. It typically consists of a glass tube filled with mercury or a liquid, with one end closed and the other end open. As the air pressure changes, it causes the liquid in the tube to rise or fall, providing a measurement of the pressure. Therefore, a barometer is the correct device for measuring air pressure.

The increase in temperature caused by drawing the cylinder next to the barbecue leads to an increase in pressure inside the cylinder. This increase in pressure causes the gas in the cylinder to expand, resulting in an explosion.

The molecule C6H12O6 is composed of 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. This can be determined by the chemical formula C6H12O6, which indicates the number and type of atoms present in the molecule.

An implosion occurs when the air pressure outside an object is significantly greater than the air pressure inside the object. This is because the higher external pressure causes the object to collapse inwardly, resulting in an implosion.

The correct answer is "Is a repeat function used to repeat often used functions." This answer accurately describes the purpose of a repeat function in robotics. A repeat function allows for the repetition of frequently used functions, which can be helpful in programming tasks such as making a square. It eliminates the need to manually repeat the same set of instructions multiple times, making the code more efficient and concise.

When carbon dioxide is bubbled through a liquid, it reacts with the liquid to form a white precipitate called chalk residue. This reaction occurs when carbon dioxide reacts with calcium hydroxide in the liquid, forming calcium carbonate, which is insoluble and appears as a milky white color. This test is commonly known as the limewater test because it involves using limewater, which is a solution of calcium hydroxide, to detect the presence of carbon dioxide.

A sudden drop in barometric pressure indicates that very unsettled weather is approaching, characterized by strong winds and rain. Barometric pressure is a measure of the weight of the atmosphere above a specific location. When the pressure drops rapidly, it usually means that a low-pressure system is moving in, which is often associated with stormy weather. The drop in pressure indicates that the air is rising and condensing, leading to the formation of clouds and precipitation. The strong winds and rain are typical of unsettled weather conditions.

The chemical equation given in the question is commonly known as the photosynthesis equation. Photosynthesis is the process by which plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into glucose and oxygen. This equation represents the reaction that occurs during photosynthesis, where carbon dioxide and water are converted into glucose and oxygen with the help of sunlight and chlorophyll.

Nitrogen is the most abundant gas in the Earth's atmosphere, making up approximately 79% of the total volume of gas. It is an essential component for the survival of many organisms and plays a crucial role in various biological and chemical processes. Oxygen, although important for supporting life, is present in a lesser amount compared to nitrogen. Argon and krypton are present in trace amounts and do not contribute significantly to the Earth's atmosphere.

The correct answer is "Solids move more than liquids because their particles are closer together." This statement is incorrect because in reality, solids have particles that are tightly packed together and have limited movement compared to liquids.

The PIGIBAAC system in science refers to the process of exploring ideas and solving problems. It stands for Problem, Information, Generate Hypothesis, Investigate, Analyze Data, Apply Conclusion. This system provides a structured approach for scientists to follow when conducting experiments or investigations. By using the PIGIBAAC system, scientists can effectively explore and test ideas, gather and analyze data, and draw conclusions based on evidence. Therefore, the statement "The PIGIBAAC system in science is used as a way of exploring ideas and solving problems" is true.

The diagram represents the different phase changes of a substance. Sublimation is the process in which a substance changes directly from a solid to a gas without going through the liquid phase. Condensation is the process in which a gas changes into a liquid. Solidification is the process in which a substance changes from a liquid to a solid. Therefore, the correct answer is a = sublimation, b = condensation, c = solidification.

The correct answer is A yellow programmable robot. This is because an RCX is a type of robot that is programmable and can be controlled to perform various functions. It is specifically described as yellow in color, distinguishing it from other types of robots. The other options mentioned, such as a small black "Sending tower" connected by USB or a program used for creating robotic functions, do not accurately describe what an RCX is in the context of robotics.

The program that the student has made will cause the RCX to go forward at speed 3 for 2 seconds, then turn right sharply for 2 seconds. This sequence will be repeated twice, resulting in the RCX performing the same movements a total of two times.

The correct answer suggests that as the height (altitude) increases, the pressure decreases. This conclusion is drawn from studying the graph of air pressure and altitude. The graph shows a negative correlation between height and pressure, indicating that as the altitude increases, the pressure decreases. Therefore, the correct answer accurately interprets the relationship between height and pressure based on the given graph.

When the gun powder quickly changes from a solid into a gas, it creates an area of low pressure as the gas takes up more room than the solid. This difference in pressure causes the bullet to be forced out of the gun, as the gas wants to move from an area of high pressure to an area of low pressure.

The correct answer is that it is a chemical change because the sugar has changed into carbon. When sulphuric acid is added to sugar, a chemical reaction called dehydration occurs. This reaction breaks down the sugar molecules, releasing water and leaving behind a carbon residue. The change in color from white to dark black indicates a chemical transformation, rather than a simple dissolution. Additionally, the sweet smell suggests the formation of new compounds. Therefore, this is a chemical change rather than a physical change.

The correct answer is to set Motor A forward, power level 5, and Motor C backwards, power level 5. This configuration will cause Motor A to spin in the clockwise direction (right-hand spin) at a higher power level, while Motor C spins in the counterclockwise direction at the same power level. This combination of opposite directions and equal power levels will result in a right-hand spin.

The taper test is used to check for the presence of oxygen gas. In this test, a glowing taper (a thin strip of wood or paper) is brought near the gas being tested. If the gas is oxygen, the taper will reignite and burn more vigorously. This is because oxygen supports combustion and helps in the burning process. Therefore, by observing the behavior of the taper, scientists can determine if the gas produced during a reaction is indeed oxygen.

An independent variable is what is being changed. In this prac the student is changing the gases to understand which heats up quicker.

Magnetism has a stronger force on larger objects.
Magnetism only attracts (magnets can repel)

When the can is heated on a stove, the water inside it starts to evaporate, creating steam. As the steam is trapped inside the can, it increases the pressure inside the can. When the can is inverted and placed in cold water, the steam rapidly condenses back into water, causing a decrease in pressure inside the can. The pressure outside the can, which is the atmospheric pressure, remains high. This difference in pressure between the inside and outside of the can causes the can to implode and be crushed. Therefore, the correct answer is "The high pressure of the atmosphere crushing the weakened can."

Magnetism only acts on metallic objects over a short distance.

The correct answers are:
1. If the weather balloon started out fully inflated it would pop before achieving a great height.
2. A weather balloon starts out semi-deflated because as it climbs in the air there is less pressure so the balloon will expand.

The first statement is correct because if the weather balloon is fully inflated, the increasing atmospheric pressure as it rises would cause the balloon to burst before reaching a significant height.

The second statement is correct because as the weather balloon ascends, the atmospheric pressure decreases, causing the balloon to expand. Starting with a semi-deflated balloon allows for this expansion without bursting.

A vacuum is an area devoid of any particles, so the pressure in a vacuum is zero or close to zero. Air will rush into a vacuum because it is an area of very low pressure. A vacuum can be created in a laboratory using a vacuum pump.