CHEMISTRY MODEL QUESTION PAPER

SET 4

1. When 2 g of H2 reacts with 32 g of O2 to form water. Hydrogen acts as limiting reagent.
a) What is a limiting reagent ? (1 Score)
b) Find the limiting reagent when 10 g of N2 reacts with 5g of H2. Find the mass of product
formed. Also find the limiting reagent (3 Scores)
OR
2. When sulphur reacts with oxygen two types oxides can be formed.
a) Explain which law of combination is applied here. (2 Scores)
b) Calculate the number of moles in the following.
i) 4g of CH4 ii) 12g of NaOH (2 Scores)
3. Chemical properties of an element is explained by its electronic configuration.
a) Give the electronic configuration of nitrogen. Name the principle behind this. (2 Scores)
b) Write the quantum number values of the valence electron of K. (1 Score)
c) What are the conclusions of Rutherford ‘s scattering experiment? (2 Scores)
4. The first ionization enthalpy value of group 13 elements are
B Al Ga In Tl
801 577 579 558 589
How would you explain this variation from the general trend? (3 Scores)
OR
5. Consider the following species
N3-,O2-, F-,Na+, Mg2+ and Al3+
a) What are iso electronic species? (1 Score)
b) Arrange the above species in the increasing order of their ionic radii ? (2 Scores)
6. Stability of a molecule can be explained by bond order.
a) Calculate the bond order of the following and discuss their stability.
i)He2 ii) O2
- (3 Scores)
b) Although geometries of NH3 and H2O molecules are distorted tetrahedral bond angle in
water is less than that of ammonia . Give reason. (2 Scores)
8. a) Calculate the standard enthalpy of formation of CH3OH(l) from the following data:
OR (3 Scores)
b) The reaction of cyanamide , NH2CN(s) ,with dioxygen was carried out in a bomb
calorimeter ,and ΔU was found to be – 742.7 KJ/mol at 298 K .Calculate the enthalpy
change for the reaction at 298 K.
NH2CN(g) + 3/2 O2(g) N2(g) + CO2 (g) + H2O(l) (3 Scores)
c) Give the relation between Gibbs energy change, enthalpy change and
temperature. (1 Score)
9. Blood is an example for buffer solution.
a) Explain the classification of buffer solution with suitable example (3 Scores)
b) Identify the conjugate acid – base pairs from the following reaction
(2 Scores)
c) Define PH of a solution (1 Score)
10. Redox reaction is one in which oxidation and reduction occurs simultaneously
a) Give an example for a redox reaction and Identify the oxidising and educing agent
(3 Scores)
b) Write the oxidation numbers of the under lined elements in the following.
i ) Mn O4
- ii) H2 S O4 (1 Score)
11. Heavy water is used in nuclear reactors.
a) Differentiate between ordinary water and heavy water. (1 1/2 Scores)
b) Classify the following hydrides
NH3, CaH2, CH4, NaH, NiH0.6- 0.7,LaH3 (1 1/2 Scores)
12. Gypsum and Plaster of Paris are Calcium sulphates.
a) How do they differ from each other. (1 Score)
b) Explain the preparation of plaster of paris (2 Scores)
13. Match the following.
A B C
Silicones B2H6 Water repellent
Borazine (R2SiO)n Cement
Silicates B3N3H6 Banana bond
Diborane SiO4
4- Inorganic benzene
(4 Scores)
14. Organic compounds exhibit isomerism
a) Give two conformational isomers of ethane (2 Scores)
OR
b) Give two stereo isomers of but-2-ene (2 Scores)
c) Give the IUPAC names of the following
i)
ii) (2 Scores)
d) How can you separate a mixture containing an orange and blue dye(2 Scores)
15. Complete the following reactions.
a) 2CH3CH2Br +2 Na ether
b) CH3CH2Br + Zn HCl
c) (3 Scores)
16. How are the following conversions carried out
i) Benzene to nitro benzene
ii) Butane to 1-bromo butane
iii) Ethanoic acid to methane (3 Scores)