N2 and O2 are converted to monopositive cation N2+ and&

Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

The number of electrons, neutrons and protons in a species are equal to 10, 8 and 8 respectively. The proper symbol of the species

  • O816

  • O2-816

  • O-816

  • O818


2.

A 600 W mercury lamp emits monochromatic radiation of wavelength 331.3 nm. How many photons are emitted from the lamp per second? (h = 6.626 x 10-34 Js; velocity of light = 3×108 ms-1).

  • 1 × 1019

  • 1 × 1022

  • 1 × 1021

  • 1 × 1023


3.

The shortest wavelength in hydrogen spectrum of Lyman series when RH = 109678 cm-1 is

  • 1002.7 Å

  • 1215.67 Å

  • 1127.30 Å

  • 911.7 Å


4.

Which of the following statements is false?

  • H2  molecule has 1σ bond 

  • Acetylene molecule has 3σ bonds and 3Π bonds

  • HCl molecule has 1σ bond

  • Water molecule has 2σ bonds and two lone pairs


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5.

N2 and O2 are converted to monopositive cation N2+ and O2+respectively. Which is incorrect?

  • In N2+, the N-N bond weakened.

  • In O2+, the bond order increases

  • In O2+, paramagnetism decreases

  • N2+  becomes diamagnetic


D.

N2+  becomes diamagnetic

MO configuration of N2 molecule is(σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(π2px)2(π2py)2(σ2pz)2Bond order of N2=10-42=3MO configuration of N2+ is(σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(π2px)2(π2py)2(σ2pz)1Thus, N2+ becomes paramagnetic bond order of N2+=9-42= 2.5 and bonder  bond energy. In N2+, the N-N bond is weakened.MO configuration of O2 is(σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(σ2pz)2(π2px)2(π2py)2(π*2px)1 (π*2py)1 bond order= 10-62= 2MO configuration O2+(σ1s)2(σ*1s)2(σ2s)2(σ*2s)2(σ2pz)2(π2px)2(π2py)2(π*2px)1 bond order= 10-52= 2.5Hence,O2 and O2+  both are paramagnetic, but in O2+ paramagnetic decreases.


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6.

A netural molecule XF3 has a zero dipole moment. The element X is most likely

  • chlorine

  • boron

  • nitrogen

  • carbon


7.

56 g of nitrogen and 96 g of oxygen are mixed isothermally and at a total pressure of 10 atm. The partial pressures of oxygen and nitrogen (in atm) are respectively

  • 6,4

  • 4,6

  • 5,5

  • 2,8


8.

How much time (in hours) would it take to distribute one Avogadro number of wheat grains, if 1020 grains are distributed each second?

  • 0.1673

  • 1.673

  • 16.73

  • 167.3


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9.

The first () and second (ΔH2) ionisation enthalpies (in kJ mol-1) and the (ΔegH) electron gain enthalpy (in kJ mol-1) of the elements I, II, III, IV and V are given below
Element ΔH1 ΔH2 ΔegH
I 520 7300 -60
II 419 3051 -48
III 1681 3374 -328
IV 2372 5251 +48

The most reactive metal and the least reactive non-metal of these are respectively

 

  • I and IV

  • IV and II

  • II and IV

  • III and IV


10.

Calculate the standard enthalpy change (in kJ mol-1) for the reaction

    H2(g) + O2(g) → H2O2(g)

Given that bond enthalpies of H-H, O=O, O-H and O-O (in KJ mol-1) are respectively 438, 498, 464 and 138.

 

  • -130

  • -65

  • +130

  • -334


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