Which among the following is the correct arrangement of halogens in the increasing order of their oxidizing nature ?
- A.F, Cl, Br, I
- B.Cl, Br, F, I
- C.Br, I, Cl, F
- D.I, Br, Cl, F
Correct answer
Explanation
The correct answer is D, I, Br, Cl, F. Oxidising power of the halogens falls as we go down group 17, so iodine is the weakest and fluorine the strongest oxidising agent.
An oxidising agent works by taking electrons. Fluorine is the smallest halogen and the most electronegative element, and its F–F bond is weak, so it grabs electrons more readily than any other element. Going down the group from fluorine to chlorine, bromine and iodine, atoms grow larger and hold an extra electron less firmly, so oxidising power drops. That is why chlorine can push bromine and iodine out of their salts, but iodine cannot displace any of the others.
A is wrong because it is the decreasing order, the exact reverse. B is wrong because it puts fluorine below chlorine and bromine and iodine above it. C is wrong because it places bromine below iodine, while bromine is the stronger oxidiser of the two.
Exam tip: oxidising power F > Cl > Br > I; a higher halogen displaces a lower one from its salt.
Practice Questions
View allWhich one of the following features is an indication for modification of stem of a plant?
- A.Presence of 'eye' on potato
- B.'Scale' found in onion
- C.'Tendril' found in pea
- D.'Hair' present in carrot
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The eyes of a potato are nodes with buds, and only a stem bears nodes and buds, so they prove that the potato is a modified stem.
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- A.Tungsten
- B.Copper
- C.Rubidium
- D.Aluminium
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Rubidium, an alkali metal like caesium, gives off electrons easily when light falls on it, so it is used in photoelectric cells.
Read the full explanation →Tooth enamel is made up of which one of the following calcium compounds ?
- A.Calcium carbonate
- B.Calcium sulphate
- C.Calcium hydroxide
- D.Calcium phosphate
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Tooth enamel is made mainly of calcium phosphate in the form of a hard crystal called hydroxyapatite. Enamel is the hardest substance in the human body, harder even than bone.
Read the full explanation →Which one of the following viruses used to be responsible for highly infectious disease Smallpox ?
- A.Adenovirus
- B.Variola virus
- C.Aichi virus
- D.Coxsackie virus
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Smallpox was caused by the variola virus, a large DNA virus of the pox family that spread from person to person through the air.
Read the full explanation →After fertilization, the fruit and the seed are produced by
- A.ovule and ovary, respectively
- B.ovary and ovule, respectively
- C.ovary, no ovule required
- D.ovule, no ovary required
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After fertilisation the ovary of the flower grows into the fruit, and each ovule inside it develops into a seed.
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