HALOGENS

Multiple Choice Questions

Q1. Halogens have many useful applications in our daily lives. But some halogen compounds have a negative impact on the environment. A halogen compound that depletes the ozone layer in the atmosphere is

A. sodium fluoride

B. chlorofluorocarbon

C. hydrogen fluoride

D. polytetrafluoroethylene

Q2. Chlorine water bleaches coloured materials due to the presence of

A. hypochlorous acid

B. chloride ion

C. hydrochloric acid

D. hydrogen ion

Q3. Fluorine is the most electronegative element because it

A. exhibits positive oxidation state

B. has variable oxidation state

C. has negative oxidation state

D. has low nuclear charge

Q4. What is the number of electron(s) required by halogen to form halide ion?

A. 17

B. 8

C. 7

D. 1

Q5. The chlorine reacts with hydrogen to form hydrogen chloride. Chlorine being more electronegative attracts a shared paired of electrons towards itself. What type of compound is formed with respect to the formation of HCl?

A. non-polar covalent compound

B. polar covalent compound

C. ionic compound

D. metallic compound

Q6. The correct order of increasing electronegativity of the halogens is

A. F < Cl < I < Br

B. I < Cl < Br < F

C. F < Cl < Br < I

D. I < Br < Cl < F

Q7. What would be the effective nuclear charge experienced by the electrons of a fluorine atom in ‘L’ shell?

A. 5

B. 6

C. 7

D. 8

Q8. Dechen was provided with the unknown halogen ‘X’. The halogen ‘X’ when dissolved in water turned orange-red. Dechen concluded that the halogen provided is:

A. Fluorine

B. Chlorine

C. Bromine

D. Iodine

Q9. Which of the following halogens is radioactive in nature?

A. Bromine

B. Astatine

C. Chlorine

D. Fluorine

Q10. The correct electronic configuration of fluoride ion is

A. 2, 7

B. 2, 8

C. 2, 8, 7

D. 2, 8, 8

Q11. The periodic property of halogens which increases from fluorine to iodine is

A. Atomic size

B. Electron affinity

C. Electronegativity

D. Ionization energy

Q12. Which of the following is the most electronegative element?

A. Fluorine

B. Chlorine

C. Bromine

D. Iodine

Q13. Tshering added a substance ‘X’ from halogen group in a beaker of water. Then he observed that the solution has turned to pale green colour. Name the substance ‘X’. 

A. Fluorine

B. Chlorine

C. Bromine

D. Iodine

Q14. Which of the following statements best describes the characteristics of ionization energy?

1. Ionization energy decreases across the period.
2. Ionization energy increases across the period.
3. Ionization energy decreases across the group.
4. Ionization energy increases across the group.

A. 1 and 2

B. 2 and 3

C. 3 and 4

D. 4 and 1

Q15. The elements of group VII A in the Periodic Table are called

A. alkaline earth metals.

B. alkali metals.

C. inert gases.

D. halogens.

Q16. On moving down a group in the Periodic Table, the electronegativity of the elements

A. increases.

B. decreases.

C. remains same

D. decreases and then increases.

Short Questions

Q1. Why does chlorine have a lesser value of electron affinity than chlorine?

Ans.: It is due to the small size of fluorine atom OR

 Due to electron-electron repulsion

Q2. The bleaching action of chlorine is due to _______________.

Ans.: Oxidation

Q3. The halogen used in toothpaste is _______________.

Ans.: Fluorine

Q4. Why halogens are usually stored in glass containers?

Ans.: Halogens are highly reactive or corrosive.

Q5. The electronic configuration of an element ‘X’ is:

K L M

2 8 7

i) What will be the chemical formula of the compound when magnesium combines with X?

Ans.: MgX₂

ii. Is the element ‘X’ electropositive or electronegative? Why?

Ans.: Element X is electronegative because it receives or accepts an electron.

Q6. The type of chemical bond present in the common salt.

Ans.: Ionic bond

Q7. Name the Ions formed by losing one or more electrons by an atom.

Ans.: Cation (positively charged ion)

Q8. Although halogens and their compounds can be toxic, some are essential for the human body’s functioning and are used in everyday products. Which halogen is used to manufacture non-stick plastics in the cooking pans?

Ans.: Fluorine

Q9. Two reagent bottles A and B containing solutions of Potassium Chloride and Potassium Iodide respectively have lost their labeling. Devise a chemical test to identify the solutions A and B.

Ans.: Reaction with chlorine: Potassium chloride (KCl) does NOT show any reaction with chlorine whereas potassium iodide (KI) changes colour. It is because chlorine being more reactive, displaces iodine from the solution.

KCl + Cl₂      →      No reaction

KI  +  Cl₂      →     KCl  + I₂   (Colour changes)

Q10. Fill in the following space.

Elements	Nuclear charge	Shielding electron	Effective nuclear charge
Element X	+7	A……….	+5
Element Y	B………….	10	+4
Element Z	+19	18	C…………..

Ans.:  

A. 2                

B. +14            

C. +1

Q11. Define shielding effect

Ans.: The reduction in the nuclear charge on the electron cloud, due to a difference in the attraction forces of electron on the nucleus. OR

The shielding effect is when the electron and the nucleus in an atom have a decrease in attraction which changes the nuclear charge. OR

Reduction of effective nuclear charge of an atom due to shielding electron.

Q12. The displacement reaction of halogens with halide ions shows the oxidizing power of halogen and reducing power of the halides in aqueous solution. Is the given reaction feasible? Give ONE reason

Br₂  +  2I^–      →     ?

Ans.: Yes

Reason: Bromine can displace iodine because bromine is more reactive than iodine.     OR

Bromine is powerful oxidising agent than iodine.

Q13. The reaction of Sodium with chlorine to form sodium chloride is an example of redox reaction. Use to chemical reaction given below to answers the following questions

Identity the processes X and Y

Ans.:

X- Reduction

Y-Oxidation

Q14. Define redox reaction

Ans.: A chemical reaction that involves simultaneous oxidation and reduction reaction. OR

A redox reaction is a type of chemical reaction that involves a transfer of electrons between two species/atoms

Q15. The atomic numbers of the elements of group 17 of the modern periodic table are listed below. Study the data carefully and answer the questions that follow:

Group 17 element	F	Cl	Br	I	At
Atomic number	9	17	35	53	85

i) Name the volatile liquid and volatile solid.

Ans.: Volatile liquid: Bromine

        Volatile solid: Iodine

ii) An element with four isotopes.

Ans. Chlorine

iii) Name the element that bursts into flames if bubbled through water.

Ans.: Fluorine

Q16. An element ‘X’ has the atomic number of 9. To which period and group does the element ‘X’ belong?

Ans.:

e.c. of X is 2, 7

So, it belongs to 2^nd period and group 17

Q17. Bleaching is the process of removing the colours from coloured organic matter by using chemical agents.                      

Raw wood pulp     →       Bleached wood pulp

In the above equation, raw wood pulp is bleached using a bleaching agent.

i) Name the bleaching agent used.

Ans.: Chlorine

ii) Mention the bleaching property of the above element.  

Ans.: Oxidising property

Q18. Complete the following table with regards to the periodic table trends in physical properties.

Properties	Across the period	Down the group
Atomic radius	A …………..	B …………..
Ionization energy	C …………..	D …………..

Ans.:

A. Decreases    

B. Increases  

C. Increases  

D. Decreases

Q19. From the chemical reactions,   

I_2(g) + 2e^– → 2I^– _(aq)

2I^–_(aq) → I_2(aq) + 2e^–

Write the reaction that undergoes

i) Oxidation

Ans.: 2I^–_(aq) → I_2(aq) + 2e^–, as there is losing of electrons

ii) Reduction

Ans.: I_2(g) + 2e^– → 2I^– _(aq), since it gains electrons.

Compiled from BCSE 2017-2021