ratio_divide","color":"green","label":"simplify"},{"to":"formula","from":"ratio_simple","color":"teal","label":"use as subscripts"}]},"order":3,"title":"Make the whole-number ratio","description":"Divide both mole amounts by the smaller value, 0.01. This gives the simplest whole-number ratio, K:O = 2:1, so the empirical formula is K₂O. This earns the final answer mark."}]}],"generatedAt":"2026-07-21T05:04:34.625Z","modelVersion":"gpt-5.6-terra","explanationVersion":"v3"},"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"5b720a29-28c0-4b0b-bf6e-20149e04064b","revisionId":"0b4c0e55-a6f8-4f2e-b714-330c34cd6b67","questionNumber":null,"questionType":"LA","specification":"","difficulty":7,"difficultyBand":"medium","totalMarks":2,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"4d408722-ea91-401f-8c14-5279561a260c","label":null,"content":"Calculate the total number of atoms in $15.0\\text{ g}$ of glycine, $\\text{C}_2\\text{H}_5\\text{NO}_2$.\n\n(relative formula mass: $\\text{C}_2\\text{H}_5\\text{NO}_2 = 75$; Avogadro constant = $6.02 \\times 10^{23}$)","markscheme":"- Calculates the number of moles of glycine as $\\frac{15.0}{75} = 0.20$ mol (or total moles of atoms as $2.0$ mol) M1\n- Calculates the total number of atoms as $10 \\times 0.20 \\times 6.02 \\times 10^{23} = 1.20 \\times 10^{24}$ (or $1.204 \\times 10^{24}$) A1","marks":2,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null},{"id":"5da260d9-5ab0-4277-a9af-2bfc2fd81ef5","revisionId":"767c3ff4-1826-4cad-a4e3-63463c09a058","questionNumber":null,"questionType":"LA","specification":"","difficulty":4,"difficultyBand":"medium","totalMarks":3,"sourceTitle":null,"calculatorUse":null,"parts":[{"id":"dcbfb106-b86b-4f17-bc80-b7da74157990","label":null,"content":"Calculate the relative formula mass of a poly(styrene) polymer chain containing 6130 styrene monomer units, $\\text{C}_8\\text{H}_8$.\n\n(relative atomic masses: $\\text{H} = 1.0$, $\\text{C} = 12.0$)\n\nGive your answer to three significant figures.\n\nShow your working.","markscheme":"- Calculates the relative formula mass ($M_r$) of one styrene monomer, $\\text{C}_8\\text{H}_8$: $(8 \\times 12.0) + (8 \\times 1.0) = 104.0$ M1\n- Multiplies the monomer mass by the number of units: $6130 \\times 104.0 = 637,520$ M1\n- Rounds the final answer to three significant figures to give $638,000$ (or $6.38 \\times 10^5$) A1","marks":3,"order":0,"markingRubric":null,"explanation":null,"options":[]}],"options":[],"explanation":null,"firstAttemptFullMarks":null}],"subjectCode":"gcse_chemistry","summaries":[{"id":"0022739c-a336-4f02-b237-23301e5ab290","difficultyBand":"medium","calculatorUse":null},{"id":"00a695e1-8f94-48c2-9ede-d32dde228113","difficultyBand":"medium","calculatorUse":null},{"id":"03c04d6b-1955-4456-84ef-f2ad729be875","difficultyBand":"easy","calculatorUse":null},{"id":"06b9594e-3eea-4ab8-bb79-128debcd69a8","difficultyBand":"medium","calculatorUse":null},{"id":"071115fb-bca3-4b14-a6ad-fec7ce84b5ce","difficultyBand":"medium","calculatorUse":null},{"id":"0824b601-d441-453f-aea8-4a33937d2ca4","difficultyBand":"medium","calculatorUse":null},{"id":"0927ff25-5f33-4482-b3f6-845eed9dda56","difficultyBand":"medium","calculatorUse":null},{"id":"095f0386-0224-4019-9436-c450eeeedee2","difficultyBand":"medium","calculatorUse":null},{"id":"0ad6f0c0-37a6-4bc9-9e56-65cbf20690f3","difficultyBand":"medium","calculatorUse":null},{"id":"0b657b9b-ef60-48f0-bad1-f87f94ad702f","difficultyBand":"easy","calculatorUse":null},{"id":"0d460fbc-6e0d-417c-a23e-5c6c661a65b4","difficultyBand":"medium","calculatorUse":null},{"id":"0dea3bb4-9f93-4eff-b73a-4155fd946467","difficultyBand":"easy","calculatorUse":null},{"id":"0e60d318-d882-419c-adb3-1d55a67dc61e","difficultyBand":"medium","calculatorUse":null},{"id":"0f723133-903b-4fbe-8028-251a9a4c185e","difficultyBand":"medium","calculatorUse":null},{"id":"100a3d9a-9b7d-428e-bb5b-1638f1e4f673","difficultyBand":

Calculations involving masses

Question 44

Calculations involving masses Questions

Calculations involving masses

Question 44

Calculations involving masses Questions