Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Principles of Chemistry
991 practice questions
Topics covered
- States of Matter102 practice questions
- Elements, Compounds and Mixtures69 practice questions
- Atomic Structure108 practice questions
- The Periodic Table103 practice questions
- Chemical Formulae, Equations and Calculations Part 119 practice questions
- Chemical Formulae, Equations and Calculations Part 2144 practice questions
- Ionic Bonding143 practice questions
- Covalent Bonding68 practice questions
- Metallic Bonding19 practice questions
- Electrolysis198 practice questions
Practice questions
171–180 of 991
Question 171
7 marks · Hard
Answer and see the solution →A chemist is given two samples labelled X and Y. She suspects that X is a compound and Y is a mixture. She performs paper chromatography on both samples along with three dyes labelled D1, D2, and D3 on the same sheet.
Chromatogram for samples and dyes Distances moved by spots (all from the pencil line at the bottom of the paper) Substance Distance moved by spot (cm) Solvent front 5.0 X 2.0 Y (spot 1) 1.0 Y (spot 2) 3.0 D1 1.0 D2 2.0 D3 3.0 (a)[3 marks]Classify samples X and Y as elements, compounds, or mixtures, using the results of the chromatogram. Explain your reasoning.
(b)[2 marks]For each spot found for Y, identify which dye(s), if any, are present in Y.
(c)[2 marks]Calculate the R_f value for the spot found for X.
Question 172
1 mark · Easy
Answer and see the solution →State the meaning of the term "atom".
Question 173
3 marks · Easy
Answer and see the solution →Answer the following about atoms and molecules.
(a)[1 mark]Define a molecule.
(b)[1 mark]Give an example of a molecule formed from atoms of two different elements.
(c)[1 mark]Explain why atoms of helium (He) are not classed as molecules.
Question 174
2 marks · Easy
Answer and see the solution →A molecule of methane (CH₄) contains one carbon atom and four hydrogen atoms. Calculate the total number of atoms present in three molecules of methane. Show your working.
Question 175
2 marks · Easy
Answer and see the solution →Explain the difference between an atom of oxygen (O) and a molecule of oxygen (O₂).
Question 176
3 marks · Easy
Answer and see the solution →The table shows three simple substances. Use the information to answer the questions.
Atoms in substances Substance Atoms present Hydrogen H₂ Nitrogen N₂ Water H₂O (a)[1 mark]Which of these substances are molecules made from only one type of atom?
(b)[1 mark]How many atoms are present in one molecule of water?
(c)[1 mark]State why water is classified as a molecule.
Question 177
1 mark · Easy
Answer and see the solution →Complete the sentence: A molecule must contain
atom(s).
Question 178
3 marks · Easy
Answer and see the solution →This question is about atoms and molecules.
(a)[1 mark]State what an atom is.
(b)[1 mark]State what a molecule is.
(c)[1 mark]Describe one feature that atoms and molecules have in common.
Question 179
2 marks · Easy
Answer and see the solution →Each molecule of carbon dioxide (CO₂) contains one carbon atom and two oxygen atoms. How many atoms are present in four molecules of carbon dioxide? Show your working.
Question 180
3 marks · Normal
Answer and see the solution →A molecule of ammonia (NH₃) contains both nitrogen and hydrogen atoms.
(a)[3 marks]Calculate the total number of atoms in two molecules of ammonia (NH₃). Show your working.