Question Library

Copper (II) ions have vacant d-orbitals. This means that they can accept a pair of electrons from a donor atom. When a copper (II) ion accepts a pair of electrons, it forms a co-ordinate covalent bond with the donor atom.

Cations are discharged at the cathode during electrolysis. Electrolysis is the process of using an electric current to cause a chemical reaction to take place. The cathode is the negative electrode in an electrolytic cell. It is where cations (positively charged ions) are discharged

Carbon is deposited in the exhaust pipes of cars primarily because of incomplete combustion of petrol. When the fuel (petrol) is burned in the engine's combustion chamber, ideally, it should be fully oxidized, resulting in the production of carbon dioxide (CO2) and water vapor. However, in real-world conditions, the combustion process may not be perfect, and some of the carbon in the petrol may not fully burn. As a result, carbon particles are formed and get carried through the exhaust system.

Dalton's atomic theory cannot be explained by the application of the kinetic theory of gases because it deals with the atomic-level structure and behavior of matter, which is beyond the scope of the kinetic theory's focus on the macroscopic behavior of gas particles. The other laws (Charles' law, Gay-Lussac's law, and Boyle's law) can be well understood and explained by the kinetic theory of gases, as they relate to the macroscopic properties and behaviors of gases and their constituent particles.

There are 5 unpaired electrons present in \(_{26}Fe^{3+}\). The atomic number of iron is 26, so it has 26 electrons. When iron loses 3 electrons to form \(Fe^{3+}\), it loses 2 from the s orbital and 1 from the d orbital. This leaves 5 unpaired electrons in the d orbital. The electron configuration of \(Fe^{3+}\) is [Ar]3d5. The 5 d electrons are all unpaired because Hund's rule states that electrons will occupy degenerate orbitals singly before they pair up. This is because unpaired electrons have a lower energy than paired electrons.

Flooding is a major consequence of global warming because as the Earth's ice caps and glaciers melt, sea levels rise. This can cause flooding in coastal areas and low-lying islands. For example, in 2019, the Netherlands experienced its worst flooding in decades, with over 10,000 homes damaged and thousands of people evacuated.

Melting point increases. This is because the atoms become larger as you go down the group, which means that the metallic bonds between them become stronger.

Natural gas is a fossil fuel primarily composed of hydrocarbon gases. The primary component of natural gas is methane, which typically makes up a significant portion of the gas mixture. Methane is a simple hydrocarbon with one carbon atom and four hydrogen atoms (CH4). It is the main component of natural gas, often accounting for over 90% of its composition.

The density of a gas is directly proportional to its molar mass. This means that gases with a lower molar mass will be less dense than gases with a higher molar mass. Nitrogen (N2) has a molar mass of 28 g/mol, which is less than that of air (approximately 29 g/mol), making it less dense than air.

The periodic property that is used to determine whether a covalent molecule is polar or not is electronegativity. Electronegativity is a measure of the ability of an atom to attract electrons in a chemical bond. The greater the electronegativity of an atom, the more strongly it will attract electrons.

Molar mass of Na2SO4 = 2(Na) + S + 4(O) = 2(23.0 g/mol) + 32.1 g/mol + 4(16.0 g/mol) = 46.0 g/mol + 32.1 g/mol + 64.0 g/mol = 142.1 g/mol Now, we can calculate the number of moles of Na2SO4 in the solution: Number of moles = Mass of the salt / Molar mass Number of moles = 10.5 g / 142.1 g/mol ≈ 0.0739 mol Next, we need to find the volume of the saturated solution, given as 100 cm³, and convert it to liters: Volume of solution = 100 cm³ = 100 cm³ / 1000 cm³/dm³ = 0.1 dm³ Finally, we can calculate the solubility in mol/dm³: Solubility = Number of moles / Volume of solution Solubility = 0.0739 mol / 0.1 dm³ ≈ 0.739 mol/dm³ Rounded to two decimal places, the solubility of sodium tetraoxosulphate (VI) at 30^\circC is approximately 0.74 mol/dm³. Therefore, the correct option is: 0.74 mol dm-3. Solubility = 10.5 g / 100 cm3 * 142 g/mol = 0.739 mol/dm3

The compound that could be dried by using conc. tetraoxosulphate (VI) acid and not calcium oxide is an acid anhydride. Acid anhydrides are compounds that can react with water to form acids. When acid anhydrides are exposed to air, they will absorb water from the air and become hydrated. This can make them difficult to dry with calcium oxide, which is a base.

The statement that is not correct about gases is Gases are highly soluble in water at high temperatures. Gases are not highly soluble in water at high temperatures. The solubility of gases in water decreases as the temperature increases. This is because the kinetic energy of the gas molecules increases as the temperature increases. The increased kinetic energy of the gas molecules makes it more difficult for them to be dissolved in water.

Molarity = 0.100 mol / 0.250 mol dm3 = 0.100 mol / 0.250 dm3 * 1000 cm3/dm3 = 400 cm3 Volume (V) = Amount (n) / Concentration (C) Given that the amount of HCl is 0.100 mol and the concentration of the solution is 0.250 mol/dm³, you can calculate the volume: Volume (V) = 0.100 mol / 0.250 mol/dm³ = 0.4 dm³ Since 1 dm³ is equal to 1000 cm³, you can convert the volume from dm³ to cm³: Volume (V) = 0.4 dm³ \times 1000 cm³/dm³ = 400 cm³ Therefore, the volume of 0.100 mol of HCl in a 0.250 mol/dm³ solution is 400 cm³.

In metallic bonding, positive metal ions (cations) are surrounded by a "sea" of delocalized electrons that move freely throughout the metal lattice. This arrangement creates a cohesive force that holds the metal atoms together. The mobile electrons contribute to the unique properties of metals, such as high electrical and thermal conductivity, malleability, and ductility.