Final answer:
None of the student's options A, B, C, D are correct. The right balanced chemical equation for the reaction between calcium and oxygen to form calcium oxide is 2Ca + O2 -> 2CaO. The responses for the balance exercise provided are also correctly balanced.
Step-by-step explanation:
The subject of this question is Chemistry, specifically it involves balancing chemical equations, which is an important concept to understand chemical reactions and stoichiometry. To balance a chemical equation, each side of the equation must have the same number of atoms of each element. This ensures that the Law of Conservation of Mass is adhered to, which states that mass cannot be created or destroyed in a chemical reaction. Examining the options given by the student for a balanced equation involving calcium and oxygen, none of the options (A, B, C, D) represent a balanced chemical equation for the reaction between calcium (Ca) and oxygen (O2) to form calcium oxide (CaO). However, the correct balanced equation would be 2Ca + O2 -> 2CaO, with two atoms of calcium reacting with one molecule of oxygen to produce two formula units of calcium oxide.
Below are balanced equations for the given reactions:
- Mg + O2 → 2MgO
- Ca + 2H2O → Ca(OH)2 + H2
- CaCl2 + Na2CO3 → CaCO3 + 2NaCl
- Barium chloride reacts with sulphuric acid to produce barium sulphate and hydrochloric acid: BaCl2 + H2SO4 → BaSO4 + 2HCl