Year 9 Chemistry Test - Limestone

Glass can trap too much heat in a building during the summer because it is a poor insulator. This means that it allows heat to pass through it easily, causing the interior of the building to become hot. This can result in the need for excessive air conditioning to cool down the space, leading to increased energy consumption and higher utility bills.

Stainless steel is likely to be used for making cutlery because it is a corrosion-resistant and durable material. It contains a high percentage of chromium, which forms a protective layer on the surface of the steel, preventing it from rusting or staining. This makes stainless steel ideal for cutlery as it can withstand frequent use, exposure to moisture, and contact with acidic foods without deteriorating. Additionally, stainless steel is easy to clean and maintain, making it a practical choice for cutlery items.

A benefit of a limestone quarry is that it provides employment opportunities for local people. Quarrying operations require a workforce to extract and process the limestone, creating jobs in the local community. This can contribute to economic growth and development by providing income and livelihoods for individuals and families. Additionally, the presence of a quarry can stimulate other businesses in the area, such as transportation and construction, further boosting employment opportunities.

Transition metals are like other metals in the way that they are good conductors of electricity. This is a characteristic shared by most metals, including transition metals. Being able to conduct electricity is a property of metals due to the presence of free electrons that can move freely within the metal's structure, allowing for the flow of electrical current.

Concrete is a preferred material for building foundations because it has high compressive strength, meaning it can withstand a significant amount of force when squashed or compressed. This strength allows the foundation to support the weight of the structure above it and resist any potential settlement or movement. Additionally, concrete is also durable and resistant to many environmental factors, including acid rain, which means it can withstand long-term exposure without being worn away.

The correct answer is 96%. In a blast furnace, iron is extracted from iron ore. The iron obtained from a blast furnace is not pure, as it contains impurities such as carbon, sulfur, and other elements. The percentage of iron in the iron obtained from a blast furnace is approximately 96%, with the remaining 4% being impurities.

Limestone is mostly made of calcium carbonate. This is because limestone is a sedimentary rock that forms from the accumulation of the remains of marine organisms such as coral and shells, which are primarily composed of calcium carbonate. Over time, these remains are compressed and cemented together to form limestone. Calcium oxide and calcium hydroxide are both derived from calcium carbonate through chemical reactions, but they are not the primary components of limestone.

The correct answer is cement, sand, and crushed rock. Water is indeed one of the ingredients of concrete, but it is not the only one. Concrete is made by mixing cement, sand, crushed rock, and water together. Cement acts as a binding agent, while sand and crushed rock provide the necessary strength and stability to the mixture.

Gold can be found in the Earth's crust in its native state because it is very unreactive. Unlike other metals, gold does not easily combine with other elements or form compounds. This makes it less likely to undergo chemical reactions and allows it to remain in its pure form for long periods of time. Additionally, gold's unreactivity also contributes to its durability and resistance to corrosion, making it highly valued and sought after for various purposes throughout history.

Calcium oxide is produced from calcium carbonate by heating it. When calcium carbonate is heated, it undergoes a chemical reaction called thermal decomposition, which breaks it down into calcium oxide and carbon dioxide. This process is commonly known as calcination. The heat causes the carbonate ions in calcium carbonate to break apart, resulting in the formation of calcium oxide.

Aluminium is suitable for overhead mains electricity cables because it has a low density, which makes the cables lighter and easier to install. Additionally, aluminium is a good conductor of electricity, allowing for efficient transmission of electrical energy through the cables.

Aluminium is extracted from its ore by electrolysis because it is more reactive than carbon. Electrolysis is a process that uses an electric current to separate elements from compounds. Since aluminium is more reactive than carbon, it cannot be extracted by carbon reduction, which is a common method for extracting less reactive metals. Instead, electrolysis is used to break down the aluminium ore into its pure form. This process involves passing an electric current through a molten mixture of aluminium oxide and cryolite, causing the aluminium ions to be reduced and deposited at the cathode.

Iron is extracted from iron ore by reduction with carbon or carbon monoxide because iron is less reactive than carbon. This means that iron has a lower tendency to form compounds with other elements compared to carbon. By using carbon or carbon monoxide, the iron in the ore can be separated from the oxygen and other impurities, allowing for the extraction of pure iron. This method is cost-effective and widely used in the industry.

Titanium is expensive to extract from its ore because the extraction process involves several stages. Each stage requires specific equipment, chemicals, and expertise, which adds to the overall cost. The extraction process includes crushing and grinding the ore, followed by chemical processing to remove impurities and separate titanium from other elements. Additionally, titanium ore is relatively rare, making it more difficult and costly to mine and extract compared to other metals. This scarcity further contributes to the high cost of extracting titanium from its ore.

Electrolysis is the process used to purify copper. In this process, an electric current is passed through a copper sulfate solution, causing the copper ions to move towards the negative electrode (cathode) and deposit onto it, while impurities settle at the bottom as sludge. This method allows for the separation of pure copper from impurities, resulting in purified copper that can be used for various applications. Filtration is not the correct answer as it is a method used to separate solid particles from a liquid or gas. Reduction in a blast furnace is also not the correct answer as it is a method used to extract iron from its ore.

Slaked lime is the common name for calcium hydroxide. Calcium hydroxide is a chemical compound that is formed when calcium oxide (also known as quicklime) reacts with water. It is commonly used in various applications such as in construction, agriculture, and water treatment. Therefore, calcium hydroxide is the correct answer.

Pure iron is softer compared to steel. This is because steel is an alloy made up of iron and other elements, such as carbon. The presence of these additional elements in steel strengthens its structure and makes it harder. In contrast, pure iron lacks these additional elements, making it softer and more malleable.

Aluminium does not corrode quickly because it has a thin layer of aluminium oxide on its surface. This oxide layer acts as a protective barrier, preventing further oxidation of the metal. It forms a tight and stable bond with the underlying aluminium, making it resistant to corrosion. This oxide layer also helps to prevent the metal from reacting with other substances, such as water or oxygen, further contributing to its low reactivity and slow corrosion rate.

In a blast furnace, iron oxide is reduced to form iron. Reduction is a chemical reaction in which oxygen is removed from a substance. In this case, the iron oxide is heated with a carbon source, such as coke, which acts as a reducing agent. The carbon reacts with the oxygen in the iron oxide, causing the oxygen to be removed and leaving behind pure iron. This reduction process is an important step in the production of iron in a blast furnace.

Alloys are likely to be harder than pure metals because the addition of different elements in alloys disrupts the regular arrangement of atoms, making it difficult for layers of atoms to slide over each other. This disruption creates a stronger and more rigid structure, resulting in increased hardness compared to pure metals.