Chemistry Past Paper Questions PDF

1. What are the four atoms that make up 96 percent of every organism? - Carbon, Hydrogen, Oxygen, Nitrogen 2. Explain how covalent bonding holds molecules together. - Covalent bonds involve the sharing of electrons between atoms to create stable molecules. 3. Describe the structure of basic atom...

1. What are the four atoms that make up 96 percent of every organism? - Carbon, Hydrogen, Oxygen, Nitrogen 2. Explain how covalent bonding holds molecules together. - Covalent bonds involve the sharing of electrons between atoms to create stable molecules. 3. Describe the structure of basic atomic structure. - Atoms consist of a nucleus with protons and neutrons, surrounded by electrons. 4. What is the difference between covalent bonds and ionic bonds? - Covalent bonds involve electron sharing; ionic bonds involve electrical attraction between charged atoms. 5. What is the role of water in acid–base reactions? - Water can act as both an acid and a base, aiding in proton transfer reactions. 6. Explain the theory of chemical evolution. - Chemical evolution theory proposes that complex molecules evolved from simpler compounds in early Earth conditions. 7. What type of bond results when atoms with the same electronegativity form a covalent bond? - A nonpolar covalent bond 8. How many more protons are present in a solution with a pH of 5 compared to a solution with a pH of 7? - 100 times 9. Which type of bond needs to be broken for water to vaporize? - Hydrogen bonds 10. What describes chemical equilibrium where forward and reverse reactions continue without changing concentrations? - There are equal concentrations of products and reactants while forward and reverse reactions continue. 11. What tends to make chemical reactions spontaneous? - The reactants have lower potential energy than the products. 12. Balance the chemical equation: _ CO2 + _ H2O -> _ C6H12O6 + _ O2 - 1, 6, 1, 6 13. Is the following statement true or false: The equation is balanced. - True 14. Is the following statement true or false: The arrow indicates a reversible reaction. - True 15. Is the following statement true or false: H2O is a product in the equation. - True