Class 12 Chemistry Chapter 7 The p-Block Elements Question Answer: Here we are providing Best Solution (Question & Answer) for class 12 Subject Chemistry Chapter 7 The p-Block Elements. Students can make easily study access all the chapters of Class 12 Chemistry.
Class 12 Chemistry Chapter 7 The p-Block Elements Question Answer
Class 12 Chemistry Chapter 7 Multiple Choice questions-
1. H2S is more acidic than H2O because
(a) oxygen is more electronegative than sulphur.
(b) atomic number of sulphur is higher than oxygen.
(c) H — S bond dissociation energy is less as compared to H — O bond.
(d) H — O bond dissociation energy is less also compared to H — S bond.
2. The boiling points of hydrides of group 16 are in the order
(a) H2O > H2Te > H2S > H2Se
(b) H2O > H2S > H2Se > H2Te
(c) H2O > H2Te > H2Se > H2S
(d) None of these
3. In the manufacture of sulphuric acid by contact process Tyndall box is used to
(a) convert SO2 and SO3
(b) test the presence of dust particles
(c) filter dust particles
(d) remove impurities
4. Fluorine differs from rest of the halogens in some of its properties. This is due to
(a) its smaller size and high electronegativity.
(b) lack of d-orbitals.
(c) low bond dissociation energy.
(d) All of the these.
5. The set with correct order of acidity is
(a) HClO < HClO2 < HClO3 < HClO4
(b) HClO4 < HClO3 < HClO2 < HClO
(c) HClO < HClO4 < HClO3 < HClO2
(d) HClO4 < HClO2 < HClO3 < HClO
6. When chlorine reacts with cold and dilute solution of sodium hydroxide, it forms
(a) Cl– and ClO–
(b) Cl– and ClO2–
(c) Cl– and ClO3–
(d) Cl– and ClO4–
7. The formation of O2+ [PtF6]– is the basis for the formation of first xenon compound. This is because
(a) O2 and Xe have different sizes.
(b) both O2 and Xe are gases.
(c) O2 and Xe have comparable electro-negativities.
(d) O2 and Xe have comparable ionisation enthalpies.
8. Partial hydrolysis of XeF4 gives
(a) XeO3
(b) XeOF2
(c) XeOF4
(d) XeF2
9. Helium is preferred to be used in balloons instead of hydrogen because it is
(a) incombustible
(b) lighter than hydrogen
(c) more abundant than hydrogen
(d) non polarizable
10. The increasing order of reducing power of the halogen acids is
(a) HF < HCl < HBr < HI
(b) HI < HBr < HCl < HF
(c) HBr < HCl < HF < HI
(d) HCl < HBr < HF < HI
Class 12 Chemistry Chapter 7 Very Short Questions-
1. Write the elements of group 15?
2. Write chemical name & formulae of
a) Chile saltpetre
b) Indian saltpetre
3. What is special about the valence configuration of Group 15?
4. The atomic radii increases considerably from N to P but very little increase is observed from As to Bi. why?
5. Give reason for the following- the first ionization enthalpy of 15th group elements is higher than 16th group elements?
6. How does metallic character vary down the 15 group & why?
7. What are the common oxidation states of this group?
8. What is the maximum covalence shown by N?
9. Bi (v) is a stronger oxidizing agent than Bi (III). Why?
10. Give an example showing disproportionation of oxidation state of nitrogen?
Short Questions-
1. Write the various steps for preparation of sulphuric acid by contact process?
2. Name different sulphates formed by sulphuric acid?
3. Why are pentahalides more covalent than trihalides?
4. Why is
5. Why is
6. How does ammonia react with a solution of
7. What is the covalence of nitrogen in
8. What happens when white phosphorus is heated with concentrated NaOH solution in an inert atmosphere of
9. Write a balanced equation for the hydrolytic reaction of
10. What happens when
Long Questions-
1. Give reasons: –
(a) Oxygen molecule is diatomic whereas sulphur molecule is polyatomic.
(b) The most common oxidation state of oxygen is -2.
(c) H2O is liquid whereas
(d) The increasing order of acidic character in 16th group hydrides is
(e)
2. Discuss the different types of oxides.
3. Bond angle in
4. Comment on the nature of two S-O bonds formed in
5. Discuss the general characteristics of Group 15 elements with reference to their electronic configuration, oxidation state, atomic size, ionisation enthalpy and electronegativity.
6. Discuss the trends in chemical reactivity of group 15 elements.
7. Write main differences between the properties of white phosphorus and red phosphorus.
9. Describe the manufacture of
10. How is
Assertion and Reason Questions-
1. In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
- Assertion and reason both are correct statements and reason is correct explanation for assertion.
- Assertion and reason both are correct statements but reason is not correct explanation for assertion.
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
Assertion: Caro’s acid has S atom in +6 oxidation state.
Reason: Caro’s acid contains one peroxo O22 − group.
2. In these questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
- Assertion and reason both are correct statements and reason is correct explanation for assertion.
- Assertion and reason both are correct statements but reason is not correct explanation for assertion.
- Assertion is correct statement but reason is wrong statement.
- Assertion is wrong statement but reason is correct statement.
Assertion: HOF bond angle in HFO is higher than HOCl bond angle in HClO.
Reason: Oxygen is more electronegative than all halogens except fluorine.
Case Study Questions-
1. Read the passage given below and answer the following questions:
Chlorine is a greenish yellow gas with pungent and suffocating odour. With dry slaked lime, it gives bleaching powder. Bleaching powder is a mixture of calcium hypochlorite and basic calcium chloride:
[Ca(OCl)2· CaCl2· Ca(OH)2· 2H2O].
The amount of chlorine obtained from a sample of bleaching powder by the treatment with excess of dilute acids or CO2 is called available chlorine. Chlorine is a powerful bleaching agent. Bleaching effect of chlorine is permanent.
The following questions are multiple choice questions. Choose the most appropriate answer:
- Chlorine gas reacts with _____ to form bleaching powder.
- Ca(OH)2
- CaCl2
- CaSO4
- dry CaO
- Chlorine reacts with cold and dilute alkali to form:
- Chloride
- Hypochlorite
- Chlorate
- Both (a) and (b)
- Which of the following is produced on the reaction of bleaching powder with a few drops of cone. HCl?
- Hypochlorous acid
- Oxygen
- Chlorine
- Calcium oxide
- Chlorine is used as a bleaching agent. The bleaching action is due to.
- Oxidation
- Chlorination
- Hydrogenation
- Reduction
- Bleaching powder contains a salt of an oxoacid as one of its components. The anhydride of that oxoacid is:
- Cl2O
- Cl2O7
- ClO2
- Cl2O6
2. Read the passage given below and answer the following questions:
Noble gases are inert gases with general electronic configuration of ns2np6. These are monoatomic, colourless, odourless and tasteless gases. The first compound of noble gases was obtained by the reaction of Xe with PtF6. A large number of compounds of Xe and fluorine have been prepared till now. The structure of these compounds can be explained on the basis of VSEPR theory as well as concept of hybridisation. The compounds of krypton are fewer. Only the diftuoride of krypton (KrF2) has been studied in detail. Compounds of radon have not isolated but only identified by radio tracer technique. However, no true compounds of helium, neon or argon are yet known.
The following questions are multiple choice questions. Choose the most appropriate answer:
- The formula of the compound when Xe and PtF6 are mixed, is:
- XeF6
- XeF4
- Xe2PtF6
- Xe+[PtF6]–
- The shape and hybridisation of some xenon oxy-fluoride and fluoride compounds are given below. Find the incorrect one.
- XeOF2 – T-shape – sy3d
- XeOF4 – square pyramidal – sp3d2
- XeF2 – linear – sp3d
- XeF6 – square planar – dsp2
- Which of the following is not formed by Xe?
- XeF5
- XeF
- XeF3
- All of these.
- The number oflone pairs and bond pairs of electrons around Xe in XeOF4 respectively are,
- 0 and 5
- 1 and 5
- 1 and 4
- 2 and 3
- Which of the following compounds has more than one lone pair of electrons around central atom?
- XeO3
- XeF2
- XeOF4
- XeO2F2
Class 12 Chemistry Chapter 7 MCQ Answers-
- Answer: b
- Answer: b
- Answer: b
- Answer: b
- Answer: b
- Answer: a
- Answer: d
- Answer: b
- Answer: a
- Answer: a
Class 12 Chemistry Chapter 7 Very Short Answers-
- Ans. The elements of group 15 are Nitrogen (N), Phosphorous (P) , Arsenic (As) ,
Antimony (Sb) and Bismuth (Bi).
- Ans. (a) Chile saltpetre – Sodium nitrate – NaNO3
(b) Indian saltpetre – Potassium nitrate – KNO3 - Ans. The valence configuration of 15 group is ns2np3 the s-orbital is completely filled, and p-orbital is half filled. This half-filled orbital gives extra stability to elements of this group.
- Ans. There is a considerable increase in size from N to P as expected but due to the presence of completely filled d- orbitals which have very poor shielding effects, the increase in size is very little from As to Bi.
- Ans. Due to extra stability of half-filled configuration, the first Ionisation enthalpy of 15th group elements is higher than 16th group configuration
- Ans. The metallic character increases down the group due to decrease in ionization enthalpy and increase in size of atom.
- Ans. The common oxidation states of the group are -3, +3 & +5.
- Ans. Nitrogen shows a maximum covalence of +4 because only four orbitals, one S and three P- orbitals are available for bonding in Nitrogen.
- Ans. Bi is more stable in +3 oxidation state in comparison to +5 due to inert pair effect therefore Bi (v) has a strong tendency to act as oxidizing agent.
- Ans.
Here Nitrogen is getting oxidized to a higher oxidation state as well as reduced to a lower oxidation state.
Short Answers-
Ans 1. Contact process for sulphuric acid: –
Ans 2. The two type of sulphates are –
Ans 3. In pentahalides, the oxidation state is +5 and in trihalides, the oxidation state is +3. Since the metal ion with a high charge has more polarizing power, pentahalides are more covalent than trihalides.
Ans 4. As we move down a group, the atomic size increases and the stability of the hydrides of group 15 elements decreases. Since the stability of hydrides decreases on moving from
Ans 5. The two N atoms in
Ans 6. NH3 acts as a Lewis base. It donates its electron pair and forms a linkage with metal ion.
Ans 7.
From the structure of , it is evident that the covalence of nitrogen is 4.
Ans 8. White phosphorous dissolves in boiling NaOH solution (in a atmosphere) to give phosphine, .
Ans 9. All the bonds that are present in
Ans 10.
Long Answers-
Ans 1. (a) Oxygen being small in size forms effective and strong P
(b) Since oxygen is highly electronegative, it has little tendency to give electrons. Therefore, its most common oxidation state is -2.
(c)
(d) As we move down the group, the size of atom increases this make the bond of the element with hydrogen weak. Due to weaker bonds, the bond dissociation enthalpy decreases making the molecule more acidic. Therefore, the order of acidic strength is.
(e)
Ans 2. A binary compound of oxygen with another element is called oxide. Oxides can be simple or mixed. Simple oxides can be classified as acidic, basic Amphoteric or neutral.
An oxide that combines with water to give an acid is termed acidic oxide e.g.
An oxide that combines with water to give a base is called basic oxide e.g.
An oxide that shows characteristics of both acids and bases is Amphoteric oxide e.g.
An oxide that shows characteristic of neither acid nor base is called neutral oxide e.g. CO, NO and
Ans 3. In , P is
Concept insite: the long pair-bond pair repulsion is more than bond pair-bond pair repulsion.
Ans 4. The electronic configuration of S is
During the formation of
Both S-O bonds are equal in length (143 pm) and have a multiple bond character.
Ans 5. General trends in group15 elements
(i) Electronic configuration: All the elements in group 15 have 5 valence electrons. Their general electronic configuration is
(ii) Oxidation states: All these elements have 5 valence electrons and require three more electrons to complete their octets. However, gaining electrons is very difficult as the nucleus will have to attract three more electrons. This can take place only with nitrogen as it is the smallest in size and the distance between the nucleus and the valence shell is relatively small. The remaining elements of this group show a formal oxidation state of -3 in their covalent compounds. In addition to the -3 state, N and P also show -1 and -2 oxidation states.
All the elements present in this group show +3 and +5 oxidation states. However, the stability of +5 oxidation state decreases down a group, whereas the stability of +3 oxidation state increases. This happens because of the inert pair effect.
(iii) Ionization energy and electronegativity
First ionization decreases on moving down a group. This is because of increasing atomic sizes. As we move down a group, electronegativity decreases, owing to an increase in size.
(iv) Atomic size: On moving down a group, the atomic size increases. This increase in the atomic size is attributed to an increase in the number of shells.
Ans 6. General trends in chemical properties of group – 15
(i) Reactivity towards hydrogen:
The elements of group 15 react with hydrogen to form hydrides of type
(ii) Reactivity towards oxygen:
The elements of group 15 form two types of oxides:
(iii) Reactivity towards halogens: The group 15 elements react with halogens to form two series of salts:
(iv) Reactivity towards metals: The group 15 elements react with metals to form binary compounds in which metals exhibit -3 oxidation states.
Ans 7.
White phosphorus | Red Phosphorus |
It is a soft and waxy solid. It possesses a garlic smell. | It is a hard and crystalline solid, without any smell. |
It is poisonous. | It is non-poisonous. |
It is insoluble in water but soluble in carbon disulphide. | It is insoluble in both water and carbon disulphide. |
It undergoes spontaneous combustion in air. | It is relatively less reactive. |
In both solid and vapour states, it exists as a P4 molecule. | It exists as a chain of tetrahedral P4 units. |
8. Justify the placement of O, S, Se, Te and Po in the same group of the periodic table in terms of electronic configuration, oxidation state and hydride formation.
Ans 8. The elements of group 16 are collectively called chalcogens.
(i) Elements of group 16 have six valence electrons each. The general electronic configuration of these elements is
(ii) Oxidation state:
As these elements have six valence electrons
(iii) Formation of hydrides:
These elements form hydrides of formula
Ans 9. Sulphuric acid is manufactured by the contact process. It involves the following steps:
Step (i): Sulphur or sulphide ores are burnt in air to form
Step (ii): By a reaction with oxygen,
Step (iii):
This oleum is then diluted to obtain
In practice, the plant is operated at 2 bar (pressure) and 720 K (temperature). The sulphuric acid thus obtained is 96-98% pure.
Ans 10. Sulphur dioxide causes harm to the environment in many ways:
1. It combines with water vapour present in the atmosphere to form sulphuric acid. This causes acid rain. Acid rain damages soil, plants, and buildings, especially those made of marble.
2. Even in very low concentrations,
3. It is extremely harmful to plants. Plants exposed to sulphur dioxide for a long time lose colour from their leaves. This condition is known as chlorosis. This happens because the formation of chlorophyll is affected by the presence of sulphur dioxide.
Assertion and Reason Answers-
1. (a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
Explanation:
This can be explained through structure of caro’s acid (peroxomonosulphuric acid).
Oxidation no. of S = x, oxidation no. of H = +1,
Oxidation no. of O in peroxo linkage = -1 (each),
Oxidation no. of other oxygen atoms = -2 (each).
2 + x – 6 – 2 = 0 or x = +6.
2. (d) Assertion is wrong statement but reason is correct statement.
Explanation:
HOF bond angle in HFO is lesser than that of HOCl bond angle in HClO. Oxygen is more electronegative than all halogens except fluorine.
Case Study Answers-
1. Answer :
- (a) Ca(OH)2
- (d) Both (a) and (b)
Explanation:
In cold, chlorine reacts with dilute alkalies to form chlorides and hypochlorites.
- (c) Chlorine
- (a) Oxidation
Explanation:
Cl2 + H2O → 2HCl + [O]
- (a) Cl2O
Explanation:
Bleaching powder contains OCl– ion, hence the oxoacid is HOCl. Anhydride of HOCl is Cl2O.
2. Answer :
- (d) Xe+[PtF6]–
- (d) XeF6 – square planar – dsp2
Explanation:
XeF6 has sp3d3 hybridisation and distorted octahedral shape.
- (d) All of these.
Explanation:
Xe has completely filled 5p-orbital. As a result, when it undergoes bonding with an odd number (1, 3 or 5) of fluorine atoms, it leaves behind one unpaired electron. This causes the molecule to become unstable. As a result, XeF, XeF3 and XeF5 do not exist.
- (b) 1 and 5
Explanation:
- (b) XeF2
Explanation: XeF2 has 3 lone pairs on Xe atom.
Class 12 Chemistry All Chapter Notes & Question Answer
- Class 12 Chemistry Chapter 1 The Solid State Notes
- Class 12 Chemistry Chapter 1 The Solid State Question Answer
- Class 12 Chemistry Chapter 2 Notes
- Class 12 Chemistry Chapter 2 Question Answer
- Class 12 Chemistry Chapter 3 Electrochemistry Notes
- Class 12 Chemistry Chapter 3 Electrochemistry Question Answer
- Class 12 Chemistry Chapter 4 Chemical Kinetics Notes
- Class 12 Chemistry Chapter 4 Chemical Kinetics Question Answer
- Class 12 Chemistry Chapter 5 Surface Chemistry Notes
- Class 12 Chemistry Chapter 5 Surface Chemistry Question Answer
- Class 12 Chemistry Chapter 6 Isolation of Elements Notes
- Class 12 Chemistry Chapter 6 Isolation of Elements Question Answer
- Class 12 Chemistry Chapter 7 The p-Block Elements Notes
- Class 12 Chemistry Chapter 7 The p-Block Elements Question Answer
- Class 12 Chemistry Chapter 8 The D And F Block Elements Notes
- Class 12 Chemistry Chapter 8 The D And F Block Elements Question Answer
- Class 12 Chemistry Chapter 9 Coordination Compounds Notes
- Class 12 Chemistry Chapter 9 Coordination Compounds Question Answer
- Class 12 Chemistry Chapter 10 Haloalkanes and Haloarenes Notes
- Class 12 Chemistry Chapter 10 Haloalkanes and Haloarenes Question Answer
- Class 12 Chemistry Chapter 11 Alcohols, Phenols and Ethers Notes
- Class 12 Chemistry Chapter 11 Alcohols, Phenols and Ethers Question Answer
- Class 12 Chemistry Chapter 12 Aldehydes Ketones and Carboxylic Acids Notes
- Class 12 Chemistry Chapter 12 Aldehydes Ketones and Carboxylic Acids Question Answer
- Class 12 Chemistry Chapter 13 Amines Notes
- Class 12 Chemistry Chapter 13 Amines Question Answer
- Class 12 Chemistry Chapter 14 Biomolecules Notes
- Class 12 Chemistry Chapter 14 Biomolecules Question Answer
- Class 12 Chemistry Chapter 15 Polymers Notes
- Class 12 Chemistry Chapter 15 Polymers Question Answer
- Class 12 Chemistry Chapter 16 Chemistry in Everyday Life Notes
- Class 12 Chemistry Chapter 16 Chemistry in Everyday Life Question Answer