IX Chemistry

NOTE: Attempt Fourteen questions in all. SEVEN questions from SECTION “A”, SIX from SECTION “B” and the compulsory Q.1. All questions of SECTION “A” and “B” carry equal marks.

OBJECTIVE (Compulsory)

Q.1 (A) Fill in the blanks with the correct answers. (05)

i. A-Z indicates the number of nutrons in the nucleus of an atom.
ii. The Rule of Triad was introduced by Dobriener.
iii. The most common solvent in nature is water.
iv. 36 gm of H2O contains 2 molecules.
v. In Endothemic reaction heat is taken in.

Q.1 (B) Select the correct answer for each from the options given within brackets. (05)

i. An interpretation of the results of common tests which is a trial idea is called a/an Hypothesis.
(Experiment, Hypothesis, Prediction, Theory)

ii. Which of the following molecules contains triple covalent bond? (H2, O2, Cl2, N2)

iii. Which of the following elements will burn in oxygen to form a basic oxide?
(Sodium, Carbon, Sulphur, Phosphorus)

iv. if an element “X” forms an oxide with the formula “XO” which of the following chemical formulas is correct? (HCl, XS, XH3, X2S3)
v. Ice cubes slowly vanish from their tray while stored in a deep-freezer. This is an example of Melting. (Evaporation, Condensation, Melting, Sublimation)

SECTION “A” (Short Answer Question)

Q.2 What is a scientific method? Write the names of its four stages and describe them. (05)

Q.3. Define Molar Mass. Calculate the molar masses of the following compounds. (05)
i. Al2(SO4)3
ii. K4Fe(CN)6

Data (i)
Formula = Al2(SO4)3
= Al2S3O12
Molar Mass = ?

Solution
.. M = 2 x 27 x 3 x 3 x 12 x 16
=> M = 54 + 96 + 192
=> M = 342 g
Molar Mass = 342 g ANS

Data (ii)
Formula = K4Fe(CN)6
= K4Fe(CN)6
Molar Mass = ?

Solution
.. M = 4 x 36 x 1 x 56 x 12 + 6 x 14
=> M = 156 + 56 + 72 + 84
=> M = 368 g
Molar Mass = 398 g ANS
At. Masses: Al = 27, S = 32, O = 32, O = 16, K = 39, Fe = 5,6, C = 12, N = 14

Q.4. Write five characteristics of Cathode Rays. (05)

Q.5. What are Metaloids? Write four differences between metals and non-metals. (05)

Q.6. What is a Chemical Reaction? Define and give one example each of the following
i. Combustion Reaction
ii. Single Displacement Reaction

Q.7. Balance the following chemical equation.
i. Ba(HO3)2 ——-> BaO + NO2 + O2
2Ba (NO3)2 ——-> 2BaO + 4NO2 + O2

ii. NH3 + CO2 ——-> (NH2)2CO + H2O
4NH3 + 2CO2 ——-> 2(NH2)2CO + 2H2O

iii. PbO + O2 ——-> Pb3O4
6PbO + O2 ——-> 2Pb3O4

iv. CH4 + O2 ——-> CO2 + H2O
CH4 + 2O2 ——-> CO2 + 2H2O

v. CaCO3 + Al2Si2O7 ——-> CaSiO3 + Ca2Al2O5 + CO2
4CaCO3 + Al2Si2O7 ——-> 2CaSiO3 + Ca2Al2O5 + 4CO2

Q.8. Write five differences between Covalent Bond and Coordinate Covalent Bond. (05)

Q.9. What are Isotopes? Define the terms Mass Number and Atomic Number. Give the symbol, including the mass number and the atomic number for the atom, which has 2 fewer neutrons and 2 fewer protons than 20/10 Ne. (05)

Q.10. Define the following. (05)
i. Atomic Mass
ii. Mole
iii. Boiling Point
iv. Electron Affinity
v. Molecular Formula

Q.11. State the Law of Multiple Proportions and the Law of Reciprocal Proportions and explain any one of them what the help of an example. (05)

Q.12. What is Chemistry? Write the names of its any four branches and define tham. (05)

Q.13. What is an Ion? Write the electronic configuration of sodium ion and chloride ion. What is an Ionic Compound? Write the chemical formula of sodium chloride. (05)

SECTION “B” (Short Answer Questions)

Q.14. State the Kinetic Molecular Theory. Define the following. (05)
i. Diffusion
ii. Brownan Movement
iii. Sublimation

Q.15. Define the following. (05)
i. Saturated Solution
ii. Unsaturated Solution
iii. Super-Saturated Solution
iv. Solubility

Q.16. With the help of a labelled diagram explain the construction and working of a Lead Storage Battery.

Q.17. State Lewis concept of acids and bases and explain it with the help of an example.

Q.18. Write five differences between a solution and a suspension.

Q.19. Define Solubility. Write the names of the factors that affect solubility and describethe effect of temperature on solubility.

Q.20. Define Mole Fraction. A solution has been prepared by dissolving 2 moles of ehtyl alcohal in 3 moles of water. Calculate the mole fractions of ehtyl alcohal and water in this solution.

Data
Moles of Ethyl Alcohal = nA = 2 mol
Moles of water = nB = 3 mol
Mole fraction of Ethyl Alcohal = xA = ?
Mole fraction of water = xB = ?

Solution
.. xA = nA / nA + nB
=> xA = 2 / 2 + 3
=> xA = 2 / 5
=> xA = 0.4
=> xB = nB / nA + nB
=> xB = 3 / 2 + 3
=> xB = 3 / 5
=> xB = 0.6
Mole Fraction of Ehtyl Alcohal = xA = 0.4
Mole Fraction of Water = xB = 0.6

Q.21. Describe giving balanced chemical equations of the Solvay’s Process for the manufacture of sodium carbonate. (05)

Q.22. What is Electroplating? With the help of a labelled diagram, explain how you would electroplate an iron spoon with nickel? (05)

Q.23. Define the following. (05)
i. Nutralization
ii. Titration
iii. Salt
iv. pH
v. Double Salt