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प्रश्न
Why are halogens coloured?
उत्तर १
Almost all halogens are coloured. This is because halogens absorb radiations in the visible region. This results in the excitation of valence electrons to a higher energy region. Since the amount of energy required for excitation differs for each halogen, each halogen displays a different colour.
उत्तर २
The halogens are coloured because their molecules absorb light in the visible region. As a result of which their electrons get excited to higher energy levels while the remaining light is transmitted. The color of halogens is the color of this transmitted light.
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संबंधित प्रश्न
Iodine exists as
- polar molecular solid
- ionic solid
- nonpolar molecular solid
- hydrogen bonded molecular solid
Fluorine is a stronger oxidising agent than chlorine. Why?
Compare the oxidizing action of F2 and Cl2 by considering parameters such as bond dissociation enthalpy, electron gain enthalpy and hydration enthalpy.
Account for the following :
Acidic character increases from HF to HI.
F2 has lower bond dissociation enthalpy than Cl2. Why?
Which halogen compound in each of the following pairs will react faster in SN2 reaction CH3Br or CH3I
Give two examples to show the anomalous behaviour of fluorine.
Write two uses of ClO2.
Complete chemical reactions are:Cl2 + H2O →
Select the correct alternative from the choices given :
The correct order of increasing acidic strength of the oxoacids of chlorine is:
Cl2 acts as a bleaching agent.
Which one has the lowest boiling point?
Which of the following pairs of ions are isoelectronic and isostructural?
Bond dissociation enthalpy of E–H (E = element) bonds is given below. Which of the compounds will act as the strongest reducing agent?
| Compound | \[\ce{NH3}\] | \[\ce{PH3}\] | \[\ce{AsH3}\] | \[\ce{SbH3}\] |
| Δdiss (E – H)/kJ mol–1 | 389 | 322 | 297 | 255 |
Reduction potentials of some ions are given below. Arrange them in decreasing order of oxidising power.
| Ion | \[\ce{CIO^{-}_{4}}\] | \[\ce{IO^{-}_{4}}\] | \[\ce{BrO^{-}_{4}}\] |
| Reduction potential EΘ/V |
EΘ = 1.19 V | EΘ = 1.65V | EΘ = 1.74 V |
The reaction \[\ce{3ClO- (aq) -> ClO3- (aq) + 2Cl- (aq) + 2Cl- (aq)}\] is an example of
Write the name and formula of oxoacid of fluorine.
