Question

Q1- Answer shortly the following questions (1 marks each, Max 2 to 3 lines) (8) 1- During the reaction: aCH4 b 02cCO2 dH20, the carbon in CH is said to be oxidized. Why? 2- Define Z-scheme in photosynthesis and name the stages involved in the reaction. 3 What are the two main function of electron and proton transfer in photosynthesis? 4- The half-cell reaction of a metal M is: 5- 6- 7- 8- The standard cell potential is highly negative, the electronegativity of the metal will be large or small? What is the role of enzymes in biological processes? What are the different steps in anaerobic digestion and how they differ from fermentation? What is the difference between electronegativity and electron affinity? If you require estimating, the lower heating value of a substance how it is different from HHV estimation method in calorimetry Q2- Answer the following questions: (3) 1- 2- 3- Determine the oxidation number of P in(HPO Determine the oxidation number of Cr in (Cr20 Balance the following reaction (consider that OH ions are present in the solution) [A(OH)4]-+ N2H4 → Au + N2

Answer 1

QUESTION 1

1. The carbon in CH₄ is said to be oxidised beacause oxidation means addition of oxygen,removal of hydrogens, loss of electrons,increase in oxidation number
2. Z-scheme of photosynthesis is oxidation/reduction changes during light reactions in photo synthesis.

          the stages involved are

• light reactions capture the energy of light and use it make energy storage molecules ATP and NADPH

during second stage,light independent reactions use these products to capture and reduce co₂

5. Enzymes acts as biological catalysts and they accelrate chemical reactions

7.   Elecro negativity is the ability to attract elecrons from outside and electron affinity is the energy released when neutral atom gains eletron from outside

E.N is applied for single atom where as E.A is applied for atom /molecule

QUESTION - 2

1. Oxidation number P is +10
2. Oxidation number of Cr is +6