Create questions around graphs and tables with an AI visual question generator

Solution: Metallic bonding consists of a giant lattice of positive metal ions. These ions are surrounded by a sea of delocalised electrons that are free to move. The strong electrostatic attraction between these positive ions and the delocalised electrons holds the structure together. Covalent bonds involve sharing electron pairs, while ionic bonds involve the transfer of electrons between atoms. A mixture contains different substances that are not chemically bonded.

Solution: Metals are good conductors of electricity because the delocalised electrons are free to move through the giant metallic lattice when a voltage is applied. In contrast, simple molecular compounds like water or methane have no free electrons or ions to carry a charge, making them poor conductors. Ionic compounds only conduct when molten or aqueous because the ions are then free to move, but not in the solid state. Graphite is a non-metal that conducts, but most non-metals do not.

Solution: Metallic lattices are malleable and ductile. This is because the layers of positive ions can slide over each other when a force is applied. The sea of delocalised electrons moves with the ions, so the metallic bond is not broken. In giant covalent structures like diamond, the bonds are rigid and break if the atoms move, making them brittle. Compounds and mixtures have different physical properties based on their specific compositions.

Sample answer: A sodium atom has a proton number of 11. It has 11 electrons. The electronic configuration is 2,8,1. It has three occupied electron shells, so it is in Period 3. It has one electron in its outer shell, so it is in Group I.

Marking criteria:

• Identification of the proton number (atomic number) for the sodium atom.
• Determination of the electron arrangement (configuration) based on the proton number.
• Identification of the period and group location on the Periodic Table using the shell count and outer electrons.
• Simple reasoning connecting the shell count to the period number.

Sample answer: Isotopes are atoms of the same element. They have the same number of protons but different numbers of neutrons. Isotopes of the same element have the same chemical properties. This is because they have the same number of electrons and the same electronic configuration.

Marking criteria:

• A simple definition of isotopes focusing on protons and neutrons.
• Explanation that the proton number is the same for the same element.
• Comparison of the number of electrons to explain chemical properties.
• Reasoning that electronic configuration dictates chemical behaviour.

Sample answer: Ionic bonds form when a metal atom gives electrons to a non-metal atom. This creates positive ions and negative ions. An ionic bond is a strong attraction between these oppositely charged ions. These compounds have high melting points because the attractions in the giant lattice are very strong and need a lot of energy to break.

Marking criteria:

• Description of the transfer of electrons between a metal and a non-metal.
• Definition of the ionic bond as a strong electrostatic attraction.
• Mention of the resulting ions (cations and anions).
• Explanation of why these compounds have high melting points due to the giant lattice structure.

Sample answer: 750 g (or 750)

Marking criteria:

• To find the mass of flour needed for 18 muffins:
• Method 1 (Unit rate): 250 g ÷ 6 muffins = 41.666... g per muffin. Then 18 × (250 ÷ 6) = 18 ÷ 6 × 250 = 3 × 250 = 750 g.
• Method 2 (Scale factor): 18 ÷ 6 = 3. Multiply the original mass by 3: 250 g × 3 = 750 g.

Sample answer: £3.00

Marking criteria:

• First, find the unit price of one pencil by dividing the total cost of the pack by the number of pencils: £1.80 ÷ 6 = £0.30 (or 180 p ÷ 6 = 30 p). Next, multiply the cost of one pencil by 10: £0.30 × 10 = £3.00 (or 30 p × 10 = 300 p). The total cost is £3.00 (or 300 p).

Sample answer: 27

Marking criteria:

• Find the total number of parts by adding the terms of the ratio: 2 + 3 = 5 equal parts. Divide the total number of counters by the total parts to find the value of 1 part: 45 ÷ 5 = 9 counters. Maya's share corresponds to 3 parts: 3 × 9 = 27 counters.

Solution: To find 15% of 360 m, first find 10% by dividing 360 by 10, which gives 36 m. Then find 5% by halving 36 m, which gives 18 m. Adding 10% and 5% together (36 m + 18 m) gives 54 m. 18 m is only 5%, 36 m is only 10%, and 72 m is 20%.

Solution: To find 75% of 240, convert 75% to the fraction 3/4. First find 1/4 of 240 by dividing 240 by 4, which gives 60. Then multiply by 3 to find 3/4: 60 × 3 = 180. Therefore, 180 books were borrowed. The value 60 is only 25% (stopping after finding 1/4), 120 is 50% (half of 240), and 160 is 2/3 of 240.

Solution: First, calculate the dimensions of the enlarged poster by multiplying each side length by the scale factor of 3: width = 8 cm × 3 = 24 cm, and length = 12 cm × 3 = 36 cm. Then find the perimeter: 2 × (24 cm + 36 cm) = 2 × 60 cm = 120 cm. Alternatively, find the original perimeter first, 2 × (8 cm + 12 cm) = 40 cm, and multiply by the scale factor: 40 cm × 3 = 120 cm. 40 cm is the original perimeter without enlargement. 60 cm is the semi-perimeter (width + length) of the enlarged poster. 288 cm is the area of the enlarged poster divided by 3, or confusing area and perimeter calculations.

Solution: To find the dimensions of the enlarged rectangle, multiply each side length by the scale factor of 3: the new length is 6 cm × 3 = 18 cm, and the new width is 4 cm × 3 = 12 cm. The perimeter of the enlarged rectangle is 2 × (18 cm + 12 cm) = 2 × 30 cm = 60 cm. Alternatively, the original perimeter is 2 × (6 cm + 4 cm) = 20 cm, and multiplying the original perimeter by the scale factor of 3 also gives 20 cm × 3 = 60 cm. Therefore, the statement is True.

Solution: To find the total fraction of the bag used, add 3/5 and 3/10. Convert 3/5 to tenths: 3/5 = 6/10. Adding the amounts gives 6/10 + 3/10 = 9/10. To compare 9/10 with 4/5, convert 4/5 to tenths: 4/5 = 8/10. Since 9/10 is greater than 8/10, the statement is true.

Solution: To find the sale price, first calculate 35% of £80. 10% of £80 is £8, so 30% is 3 × £8 = £24. 5% of £80 is half of £8, which is £4. Therefore, the 35% discount is £24 + £4 = £28. Subtracting the discount from the original price gives £80 - £28 = £52. Entering 52 completes the statement correctly.

Solution: The ratio 3 : 5 gives a total of 3 + 5 = 8 equal parts. The length of one part is 72 ÷ 8 = 9 cm. The shorter piece has 3 parts, so its length is 3 × 9 = 27 cm.