Question
7. Which of these is a redox reaction? CaO+SiO_(2)arrow CaSiO_(3) B H_(2)SO_(4)+Na_(2)Oarrow Na_(2)SO_(4)+H_(2)O C NaBr+H_(2)SO_(4)arrow NaHSO_(4)+HBr D Mg+Sarrow MgS
Answer
4.6
(189 Votes)
Sarah
Master · Tutor for 5 years
Answer
C, D
Explanation
A redox reaction is a chemical reaction that describes all chemical reactions in which there is a change in oxidation state of atoms, or oi net transfer of electrons from one atom to another. Reactions that involve changes in the oxidation states of molecules in a chemical process are also classified as oxidation/reduction reactions.Option A involves neither the change in oxidation state of atoms as there's no transfer of electrons, so it is not a redox reaction. Similarly, in option B there is no net transfer of electrons between reactants i.e. no change in oxidation states therefore, it is not a redox reaction. However, in option D, We see a transfer of electrons. Mg is oxidized from Mg to Mg²⁺ (0 to +2) and S is reduced from S to S²⁻ (0 to -2). Thereby making it a redox reaction. As for Option C, it tricky because S seems to be reducing by gaining two electrons but Br seems to be oxidizing by losing one electron. It is indeed a redox as as shown in the basic process outlined in the equations HSO4⁻ + OH⁻ ---> SO4²⁻ + H2O and NaBr + ....gives..Na⁺ .... e-Therefore, option C and D are the redox reactions.