Which out of NH3 and NF3 has higher dipole moment and why?
In both molecules i.e., NH3 and NF3, the central atom (N) has a lone pair electron and there are three bond pairs. Hence, both molecules have a pyramidal shape. Since fluorine is more electronegative than hydrogen, it is expected that the net dipole moment of NF3 is greater than NH3. However, the net dipole moment of NH3 (1.46 D) is greater than that of NF3 (0.24 D).
This can be explained on the basis of the directions of the dipole moments of each individual bond in NF3 and NH3.
Since in case of NF3, fluorine is more electronegative than nitrogen, so it will attract the shared pair of electron towards itself from nitrogen. As a result dipole due to all F is in opposite direction to the resultant dipole due to N-F bonds, therefore the net dipole decreases.
In NH3, Nitrogen is more electronegative than H, so it will attract the shared pair of electrons towards itself. As a result dipole due to Nitrogen is in same direction as the resultant dipole moment due to N-H bond and hence the net dipole increases.
Hence, the net dipole moment of NF3 is less than that of NH3.
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Use molecular orbital theory to explain why the Be2 molecule does not exist.
Explain the formation of H2 molecule on the basis of valence bond theory.
Compare the relative stability of the following species and indicate their magnetic properties:
O2,O2+,O2- (superoxide), O22-(peroxide)
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Explain why BeH2 molecule has a zero dipole moment although the Be–H bonds are polar.
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BeCl2, BCl3, SiCl4, AsF5, H2S, PH3
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S and S2–; Al and Al3+; H and H–
Draw the Lewis structures for the following molecules and ions: H2S, SiCl4, BeF2, , HCOOH
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(i) CH2=C=O,
(ii) CH3CH=CH2,
(iii) (CH3)2CO,
(iv) CH2=CHCN,
(v) C6H6
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Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4
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(a) NaH2PO4
(b) NaHSO4
(c) H4P2O7
(d) K2MnO4
(e) CaO2
(f) NaBH4
(g) H2S2O7
(h) KAl(SO4)2.12 H2O
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(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only.
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a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?
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(a) B > C > Si > N > F
b) Si > C > B > N > F
(c) F > N > C > B > Si
d) F > N > C > Si > B
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6. n = 4, l = 1, ml = 0 , ms = +1/2
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(b) Select three metals that can show disproportionation reaction.
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