Halogens

Chemistry · 11th Class (Intermediate Part 1) · BISE Lahore

70 questions

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20 questions · Periodic Table and Periodic Properties × 1, Atomic Structure × 1, Chemical Bonding × 2, Stoichiometry × 1, States and Phases of Matter × 1, Chemical Energetics × 2, Reaction Kinetics × 1, Chemical Equilibrium × 1, Acid-Base Chemistry × 1, Electrochemistry × 2, Hydrocarbons × 2, Nitrogen and Sulfur × 1, Halogens × 1, Atmosphere × 1, Basic Separation Techniques × 1, Lab Safety and Practical Skills × 1

Halogens Test

10 questions · Halogens × 10

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Showing 10 of 70 questions from this chapter. The full bank is in the chapter test below.

1
Which pair of Group 17 elements consists of very rare radioactive elements?
- A.Fluorine and chlorine
- B.Bromine and iodine
- C.Astatine and tennessine (correct answer)
- D.Chlorine and bromine
Why: Astatine and tennessine are the last two members of Group 17 and are very rare and radioactive. Fluorine, chlorine, bromine and iodine are the four common halogens.
2
In the gaseous, liquid and solid states, the halogen elements exist as:
- A.Monatomic molecules
- B.Diatomic molecules (correct answer)
- C.Triatomic molecules
- D.Free ions
Why: Every halogen exists as a diatomic molecule ( $\ce{F2}$ , $\ce{Cl2}$ , $\ce{Br2}$ , $\ce{I2}$ ) in all three physical states, because the two atoms are joined by a single covalent bond.
3
At room temperature and pressure, chlorine is a gas of which colour?
- A.Pale yellow
- B.Greenish yellow (correct answer)
- C.Reddish brown
- D.Violet
Why: Chlorine is a greenish yellow gas. Pale yellow is the colour of fluorine, reddish brown is the colour of liquid bromine and violet is the colour of iodine vapour.
4
Under ordinary room conditions, bromine is best described as:
- A.A pale yellow gas
- B.A greenish yellow gas
- C.A reddish-brown volatile liquid (correct answer)
- D.A shiny greyish black solid
Why: Bromine is the only common halogen that is a liquid at room temperature. It is reddish brown and evaporates readily, giving corrosive and toxic fumes.
5
When solid iodine is warmed gently it changes directly into a violet vapour without melting. This change is called:
- A.Sublimation (correct answer)
- B.Melting
- C.Condensation
- D.Efflorescence
Why: Iodine sublimes, passing straight from the solid to the vapour state, and the vapour is violet. Melting would give a liquid, and efflorescence is the loss of water from a hydrated salt.
6
The colour of the halogens darkens progressively from chlorine to iodine mainly because of differences in:
- A.The number of lone pairs on each atom
- B.The oxidation state of the halogen in the molecule
- C.The strength of the halogen-halogen bond
- D.The absorption of light during electron transitions (correct answer)
Why: A halogen shows colour because its electrons absorb some wavelengths of visible light as they move between energy levels. These transitions shift down the group, so the colour seen becomes darker.
7
Which statement about the halogens is correct?
- A.Bromine has 35 protons and the shell structure 2, 8, 18, 7 (correct answer)
- B.Chlorine has 35 protons and the shell structure 2, 8, 7
- C.Iodine has 53 protons and the shell structure 2, 8, 18, 7
- D.Fluorine has 9 protons and the shell structure 2, 8
Why: Bromine has proton number 35 with its 35 electrons arranged 2, 8, 18, 7. Iodine has 53 protons and the structure 2, 8, 18, 18, 7, and fluorine has 9 protons with the structure 2, 7.
8
Which halogen has the highest boiling point?
- A.Fluorine
- B.Chlorine
- C.Bromine
- D.Iodine (correct answer)
Why: Boiling points rise down the group from fluorine (-188 °C) to iodine (183 °C), because the molecules become larger and the London dispersion forces between them become stronger.
9
The enthalpy change of vaporisation rises from +3.3 kJ/mol for fluorine to +30 kJ/mol for iodine. This increase shows that, down the group:
- A.The covalent bond inside the molecule becomes stronger
- B.The halogen molecules become more polar
- C.The London dispersion forces between molecules become stronger (correct answer)
- D.The molecular mass of the halogen decreases
Why: Enthalpy of vaporisation is the energy needed to separate molecules from the liquid into the gas. Larger, more polarizable molecules have stronger instantaneous dipole-induced dipole forces, so more energy is needed.
10
What is the trend in volatility of the halogens from chlorine to iodine?
- A.Volatility increases from chlorine to iodine
- B.Volatility decreases from chlorine to iodine (correct answer)
- C.Volatility is the same for all three elements
- D.Volatility rises to a maximum at bromine and then falls
Why: Chlorine is the most volatile of the three and iodine the least, because the intermolecular forces grow stronger as the molecules become larger down the group.

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