#### Term 1 Five Mark Model Questions

11th Standard

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Chemistry

Time : 02:00:00 Hrs
Total Marks : 50
10 x 5 = 50
1. The reaction between aluminum and ferric oxide can generate temperatures up to 3273 K and is used in welding metals. (Atomic mass of AC = 27 u atomic mass of O = 16 u )
2Al + Fe2O3 $\longrightarrow$ Al2O3 + 2Fe;  If in this process, 324 g of aluminum is allowed to react with 1.12 kg of ferric oxide
i) Calculate the mass of Al2O3 formed
ii) How much of the excess reagent is left at the end of the reaction?

2. Calculate the energy required for the process.
${ He }_{ (g) }^{ + }\longrightarrow { He }_{ (g) }^{ 3+ }+{ e }^{ - }$
The ionisation energy for the H atom in its ground state is -13..6 ev atom-1

3. Suppose that the uncertainty in determining the position of an electron in an orbit is 0.6 $\mathring{A}$ . What is the uncertainty in its momentum

4. Explain the diagonal relationship.

5. What is screening effect? Briefly give the basis for pauling's scale of electronegativity.

6. Explain preparation of hydrogen using electrolysis.

7. Give the uses of gypsum

8. Describe briefly the biological Importance of Calcium and magnesium

9. List the characteristics of internal energy.

10. Calculate the enthalpy change for the reaction
Fe2O3 + 3CO ⟶ 2Fe + 3CO2 from the following data.
2Fe +$\frac{3}{2}$O2 ⟶ Fe2O3; ΔH = -741 kJ
C +$\frac{1}{2}$O2 ⟶ CO; ΔH = -137 kJ
C + O2 ⟶ CO2; ΔH = - 394.5 kJ