# Chemistry 13_Objective_Phase I to VI_Paper_3

**PAPER – IV**

- Photoelectric emission is observed from a surface for frequencies n
_{1}and n_{2 }of the incident radiation (n_{1}> n_{2}). If the maximum kinetic energies of the photoelectrons in the two cases are in the ratio 1 : k then the threshold frequency n_{o}is given by

(A) (B)

(C) (D)

- Energy levels A, B, C of a certain atom corresponds to increasing values of energy i.e.

E_{A}< E_{B}< E_{C}. If l_{1}, l_{2}and l_{3}are the wavelengths of radiations corresponding to the transitions C to B, B to A and C to A respectively, which of the following statement is correct.

(A) l_{3} = l_{1} + l_{2} (B) l_{3} =

(C) l_{1} + l_{2} + l_{3} = 0 (D) l_{3}^{2} = l_{1}^{2} + l_{2}^{2}

- Three isotopes of an element have mass numbers, M, (M+1) and (M+2). If the mean mass number is (M + 0.5) then which of the following ratios may be accepted for M, (M + 1),

(M + 2) in that order

(A) 1 : 1 : 1 (B) 4 : 1 : 1

(C) 3 : 2 : 1 (D) 2 : 1 : 1.

- When photons of energy 4.25 eV strike the surface of a metal A, the ejected photoelectrons have maximum kinetic energy, T
_{A}(expressed in eV) and de Broglie wavelength l_{A}. The maximum kinetic energy of photoelectrons liberated from another metal B by photons of energy 4.20 V is T_{B}= T_{A}– 1.50 eV. If the de-Broglie wavelength of these photoelectrons is

l_{B}= 2l_{A}, then

(A) the work function of A is 2.25 eV (B) the work function of B is 4.20 eV

(C) T_{A} = 2.00 eV (D) T_{B} = 2.75 eV.

- 0.7 g of a sample of Na
_{2}CO_{3}×xH_{2}O were dissolved in water and the volume was made to 100 ml, 20 ml of this solution required 19.8 ml of N/10 HCl for complete neutralization. The value of x is

(A) 7 (B) 3

(C) 2 (D) 5

- Which graph correctly correlates E
_{cell}as a function of concentrations for the cell (for different values of M and M¢)

Zn(s) + Cu^{+2} (M) ¾® Zn^{2+}(M¢) + CuS; E^{0}_{cell} = 1.10 V

X axis: log_{10} , Y axis; E_{cell}

(A) | (B) | ||

(C) | (D) |

- A hydrogen electrode placed in a buffer solution of CH
_{3}COONa and acetic acid in the ratio’s x:y and y:x has electrode potential values E_{1}volts and E_{2}volts respectively at 25^{o}C. The pK_{a}values of acetic acid is (E_{1}& E_{2}are oxidation potential).

(A) (B) 0

(C) (D)0

- A 0.518 g sample of limestone is dissolved in HCl and then the calcium is precipitated as CaC
_{2}O_{4}. After filtering and washing the precipitate, it requires 40.0 mL of 0.250 N KMnO_{4}, solution acidified with H_{2}SO_{4}titrate as, MnO_{4}^{–}+ H^{+}+ C_{2}O_{4}^{2–}¾® Mn^{2+}+ CO_{2}+ 2H_{2}O. The percentage of CaO in the sample is

(A) 54.0% (B) 27.1%

(C) 42% (D) 84%

- An element A in a compound ABD has oxidation number A
^{n–}. It is oxidised by Cr_{2}O_{7}^{2–}in acid medium. In the experiment 1.68 ´ 10^{–3}moles of K_{2}Cr_{2}O_{7}were used for 3.26 ´ 10^{–3}moles of ABD. The new oxidation number of A after oxidation is.

(A) 3 (B) 3 – n

(C) n – 3 (D) + n

- At 40
^{o}C the vapour pressures in torr, of methyl alcohol – ethyl alcohol solutions is represented by the equation. P = 119X_{A }+ 135 where X_{A}is mole-fraction of methyl alcohol, then the value of is

(A) 254 torr (B) 135 torr

(C) 119 torr (D) 140 torr

- A substance undergoes first order decomposition. The decomposition follows two parallel first order reactions as:

The percentage distribution of B and C are:

(A) 80% B and 20% C (B) 76.83% B and 23.17% C.

(C) 90% B and 10% C (D) 60% B and 40% C

- Calculate the molal elevation constant of water which evaporates at 100°C with absorption of 536 cal/gm

(A) 0.519° (B) 0.612°

(C) 0.915° (D) 0.621°

- A radioactive isotopes decays at such a rate that after 96 minutes only 1/8th of the original amount remains. The t
_{1/2}of the nuclei is

(A) 12 minutes (B) 32 minutes

(C) 24 minutes (D) 48 minutes

- The root mean square velocity of an ideal gas is given by the expression

When the pressure is doubled at constant temperature

(A) U_{r.m.s.} increases Ö2 times (B) U_{r.m.s.} is doubled

(C) U_{r.m.s.} remains unchanged (D) U_{r.m.s. }increases by three times

- The shape of [Cu(NH
_{3})_{4}]^{2+}is square planar, Cu^{2+}in this complex is

(A) sp^{3} hybridised (B) dsp^{2} hybridised

(C) sp^{3}d hybridised (D) sp^{3} d^{2} hybridised

- Prussian blue is formed when

(A) ferrous sulphate reacts with FeCl_{3}

(B) ferric sulphate reacts with K_{4}[Fe(CN)_{6}]

(C) ferrous ammonium sulphate reacts with FeCl_{3}

(D) ammonium sulphate reacts with FeCl_{3}

- Concentrated NaOH can separate a mixture of

(A) Al^{3+} and Cr^{3+} (B) Cr^{3+} and Fe^{3+}

(C) Al^{3+} and Zn^{2+} (D) Zn^{2+} and Pb^{2+}

- The hybridisation of boron in orthoboric acid is

(A) sp^{3} (B) sp^{2}

(C) sp (D) sp^{3}d

- In concentrated sodium thiosulfate solution silver nitrate gives

(A) white ppt of Ag_{2}S_{2}O_{3} (B) soluble complex of Na_{3}[Ag(S_{2}O_{3})_{2}]

(C) Black ppt of Ag_{2}S (D) black ppt of Ag.

- Which complex is diamagnetic

(A) [Fe(CN)_{6}]^{4–} (B) [Cu(NH_{3})_{4}]^{2+}

(C) [Ti(H_{2}O)_{6}]^{3+} (D) None

- Which of the following pairs of isomers and types of isomerism are correctly matched
- [Co(NH
_{3})_{5}(NO_{2})]Cl_{2}and [Co(NH_{3})_{5}(ONO)]Cl_{2}……..linkage - [Cu(NH
_{3})_{4}] [PtCl_{4}] and [Pt(NH_{3})_{4}][CuCl_{4}] —— Coordination - [Pt(NH
_{3})_{4}Cl_{2}]Br_{2}and [Pt(NH_{3})_{4}Br_{2}]Cl_{2}.. Ionization

(A) 2 and 3 (B) 1,2 and 3

(C) 1 and 3 (D) 1 and 2

** **

- 3, 5-dimethylcyclopentene Identify major product.

(A) | (B) | ||

(C) | (D) |

- CH
_{2}= CH – CN Z is major product. So Z is

(A) | (B) | ||

(C) | (D) | EtO – CH_{2} – CH_{2} – CN |

- Which of the following compound is optically active?

(A) | CH_{2} = C = CH – Me |
(B) | |

(C) | (D) |

85. | ||||

(A) | (B) | |||

(C) | (D) | |||

- PhCHO + MeCHO

(A) Ph – CH = CH – CH_{2}OH (B) Ph – CH_{2}CH_{2} – CH_{2}OH

(C) Ph – CH_{2} – CH_{2} –– OH (D) None

87. | ||||

(A) | (B) | |||

(C) | (D) | |||

- Cyclooctatetraene is not aromatic. The reason for this is that

(A) It has eight p electrons

(B) It is a planar molecule

(C) Its structure is not that of a regular octagon

(D) Its structure can not be described by more than two canonical forms

- Which of the following compounds can be optically active

(A) | (B) | ||

(C) | CH_{2} = CH – CH_{3} |
(D) |

- Consider the following pairs of compounds

a) | |

b) |

of these pairs

(A) Both a and b are resonance forms

(B) both a and b are tautomeric forms

(C) A is a resonance pair while B is a pair of tautomers

(D) A is a pair of tautomers while B is a resonance pair

# Answers

**B**

. 62. **B** 63. **B ** 64. **D **

**C**66.**B**67.**A**- 68.
**A****B**70.**A** **B**72.**A**73.**B****C**75.**B**76.**B****B**78.**B**79.**B****A**81.**B**82.**A**- 83.
**D**84.**D****D** **A**87.**C**88.**A****D**90.**C**