SECTION-A
Read the given passage and answer the questions 1 to 5 that follows:
During the detection of elements by Lassaigne’s test the covalent compounds are converted into ionic compounds by fusion with metallic sodium. The N, S and X present in organic compounds are converted into CN-,S2- X-, which are then detected by usual test. During detection of nitrogen, if only N is present, Prussian blue color is produced and if both N and S are present blood red color is obtained in the Lassaigne’s test. Phosphorous in organic compound is detected by fusing it with Na2O2 and Na3PO4 thus formed is detected by heating with con.HNO3 and ammonium molybdate.
Q.1 Write the formula of the substance that gives Prussian blue colour in Lassaigne’s test?
Q.2 Give the reaction for the formation of blood red colored substance.
Q.3 Name the yellow precicipitate formed when phosphorus is detected in an organic compound
Q.4 Sodium nitroprusside reacts with sulphide to give purple color due to the formation of………………..
Q.5 The Lassaigne’s extract is boiled with dil. HNO3 before testing for halogens. Why?
Questions 6 to 10 are one-word answers:
Q.6 Which series of lines of the hydrogen spectrum lie in the visible region’?
Q.7 Write the IUPAC name and Symbol for the element having atomic number 120.
Q.8 Name the molecular theory that can explain magnetic character of molecules.
Q.9 Write the relationship between ΔH and ΔS.
Q.10 Define redox couple. Give one example.
Questions 11 to 15 are multiple choice questions:
Q.11 The shape of XeF4 molecule according to VSEPR theory is
(a) Square planar (b) Square pyramid (c) Tetrahedral (d) Pyramidal
Q.12 Which statement is true for reaction? H2 (g) + Cl2 (g) → 2HCl (g)
(a) ΔS = +ve (b) ΔH > ΔU (c) ΔH < ΔU (d) ΔH = ΔU
Q.13 Water gas is a mixture of
(a) CO &N2 (b) CO &H2 (c) CO2 &N2 (d) CO2 &H2
Q.14 The solubility of metal halides depends on their nature, lattice enthalpy and hydration enthalpy of the individual ions. Amongst fluorides of alkali metals, the lowest solubility of LiF in water is due to
(a) Ionic nature of lithium fluoride (b) High Lattice enthalpy
(c) High hydration enthalpy of lithium atom (d) Low ionization enthalpy of lithium atom
Q.15 The most stable halide is
(i) AlCl (ii) GaCl (iii) TlCl (iv) InCl
Question16 to 20:
(A)Both assertion and reason are correct statements and reason is the correct explanation of the assertion.
(B) Both assertion and reason are correct statement, but reason is not the correct explanation.
(C) Assertion is correct but reason is wrong statement.
(D)Assertion is wrong but reason is correct statement.
Q.16 Assertion: Electron gain enthalpy of Cl is more negative than F.
Reason: F is more electronegative than Cl atom.
Q.17 Assertion: Pi bond is never formed alone. It is formed along with a sigma bond
Reason: Pi bond is formed by axial overlap of p- orbitals only.
Q.18 Assertion: if both ΔH0 and ΔS0 are positive then the reaction will be spontaneous at high temperature
Reason: All processes with positive entropy change are spontaneous.
Q.19 Assertion: Density of ice is less than water.
Reason: Ice has open cage structure.
Q.20 Assertion: If aluminum atoms replace a few silicon atoms in three-dimensional network of silicon dioxide, the overall structure acquires a negative charge.
Reason: Aluminum is trivalent while silicon is tetravalent.
SECTION: B
Q.21 45.4 L of dinitrogen reacted with 22.7 L of dioxygen and 45.4 L of nitrous oxide was formed.
The reaction is given below:
2N2 (g) + O2 (g) → 2N2O (g)
Which law is being obeyed in this experiment? Write the statement of the law.
(OR)
Calculate the percent of carbon, hydrogen and oxygen in ethanol (C2H5OH).
Q.22 HCl is a covalent compound but it ionizes in the solution. Give reason.
Q.23 What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C.
Q.24 Derive the relationship Cp – Cv = R.
Q.25 What do you understand by term ‘autoprotolysis’ of water? What is its significance?
(OR)
Write chemical reactions to justify that hydrogen peroxide can function as an oxidizing as well as reducing agent.
Q.26 Arrange the hybrids of group 14 elements in increasing order of :
(a) Thermal stability (b) Reducing power.
(OR)
Account for the following:
(a) CO2 is a gas while SiO2 is solid at room temperature.
(b) CO2 is a gas whereas SiO2 is a high melting solid.
Q.27 (a) How is phosphorus estimated in an organic sample
(b) Draw the structural formulae of the following compounds:
(i) Ethoxypropane (ii) But-1-en-3-yne (iii) 3,4,4,-Trimethylhex-1-yne
(iv) But-2-enoic acid
(OR)
Give reason:
(a) A tertiary butyl carbocation is more stable than isobutyl carbocation. Justify.
(b) Aniline is purified by steam distillation
SECTION:C
Q.28 A compound contains 4.07% hydrogen, 24.27% carbon and 71.65% chlorine. Its molar mass is 98.96 g. What are its empirical and molecular formulas?
Q.29 Account for the following:
(a) Noble gases have very large atomic radii
(b) The electron gain enthalpy of Cl (Z = 17) is more negative than that of Fluorine (Z = 9).
(c) Ionization enthalpy of Nitrogen (Z = 7) is more than that of oxygen (Z =8).
(OR)
Explain the following:
(a) Modern Periodic law (b) Electro-negativity (c) Shielding effect
Q.30 (a) Why the compounds of group 17 with group 13 elements are more ionic and stable than with (group 1) elements?
(b) Na2O is more ionic than Li2O. why?
Q.31 A 20g chunk of dry ice is placed in an empty 0.75 litre wire bottle tightly closed what would be the final pressure in the bottle after all CO2 has been evaporated and temperature reaches to 25°C?
Q.32 Permanent ion (MnO4 –) reacts with sulfur dioxide gas in acidic medium to produce Mn2+ ion and hydrogen sulphate ion.Write ionic equation and balance by ion electron method.
Q.33 (i) Why alkaline earth metals cannot be obtained by reduction of their oxides?
(ii) Alkaline earth metals forms ionic salt having bivalent cations. Explain.Why?
Q.34 Write the mechanism of nitration of benzene.
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