NCERT Exemplar Class 12 Chemistry Chapter 7 The p-Block Elements

Candidates can download NCERT Exemplar Class 12 Chemistry Chapter 7 from this page. The exemplar has been provided by the National Council of Educational Research & Training (NCERT) and the candidates can check it from below for free of cost. It contains objective, very short answer type, short answer type, and long answer type questions. Along with it, the answer for each question has also been provided. From the NCERT Exemplar Class 12 Chemistry Chapter 7, candidates can understand the level and type of questions that are asked in the exam.

NCERT Exemplar Class 12 Chemistry Chapter 7 The p-Block Elements

NCERT Class 12 Chemistry Chapter 7 is for The p-Block Elements. The type of questions that will be asked from NCERT Class 12 Chemistry Chapter 7 are displayed in the below provided NCERT Exemplar Class 12 Chemistry Chapter 7. With the help of it, candidates can prepare well for the examination.

Also Check: NCERT Solutions for Class 12 Chemistry

Multiple Choice Questions (Type-I)

1. On addition of conc. H2SO4 to a chloride salt, colourless fumes are evolved but in case of iodide salt, violet fumes come out. This is because
   (i) H₂SO₄ reduces HI to I₂
   (ii) HI is of violet colour
   (iii) HI gets oxidised to I₂
   (iv) HI changes to HIO₃
2. In qualitative analysis when H₂S is passed through an aqueous solution of salt acidified with dil. HCl, a black precipitate is obtained. On boiling the precipitate with dil. HNO₃, it forms a solution of blue colour. Addition of excess of aqueous solution of ammonia to this solution gives _________.
   (i) deep blue precipitate of Cu (OH)₂
   (ii) deep blue solution of [Cu (NH₃)₄]²⁺
   (iii) deep blue solution of Cu(NO₃)₂
   (iv) deep blue solution of Cu(OH)₂.Cu(NO₃)₂
3. In a cyclotrimetaphosphoric acid molecule, how many single and double bonds are present?
   (i) 3 double bonds; 9 single bonds
   (ii) 6 double bonds; 6 single bonds
   (iii) 3 double bonds; 12 single bonds
   (iv) Zero double bonds; 12 single bonds
4. Which of the following elements can be involved in pπ–dπ bonding?
   (i) Carbon
   (ii) Nitrogen
   (iii) Phosphorus
   (iv) Boron
5. Which of the following pairs of ions are isoelectronic and isostructural?
   
6. Affinity for hydrogen decreases in the group from fluorine to iodine. Which of the halogen acids should have highest bond dissociation enthalpy?
   (i) HF
   (ii) HCl
   (iii) HBr
   (iv) HI
7. Bond dissociation enthalpy of E—H (E = element) bonds is given below. Which of the compounds will act as strongest reducing agent?
   
   (i) NH₃
   (ii) PH₃
   (iii) AsH₃
   (iv) SbH₃
8. On heating with concentrated NaOH solution in an inert atmosphere of CO₂, white phosphorus gives a gas. Which of the following statement is incorrect about the gas?
   (i) It is highly poisonous and has smell like rotten fish.
   (ii) It’s solution in water decomposes in the presence of light.
   (iii) It is more basic than NH₃.
   (iv) It is less basic than NH₃.
9. Which of the following acids forms three series of salts?
   (i) H₃PO₂
   (ii) H₃BO₃
   (iii) H₃PO₄
   (iv) H₃PO₃
10. Strong reducing behaviour of H₃PO₂ is due to
    (i) Low oxidation state of phosphorus
    (ii) Presence of two –OH groups and one P–H bond
    (iii) Presence of one –OH group and two P–H bonds
    (iv) High electron gain enthalpy of phosphorus
11. On heating lead nitrate forms oxides of nitrogen and lead. The oxides formed are ______.
    (i) N₂O, PbO
    (ii) NO₂, PbO
    (iii) NO, PbO
    (iv) NO, PbO₂
12. Which of the following elements does not show allotropy?
    (i) Nitrogen
    (ii) Bismuth
    (iii) Antimony
    (iv) Arsenic
13. Maximum covalency of nitrogen is ______________.
    (i) 3
    (ii) 5
    (iii) 4
    (iv) 6
14. Which of the following statements is wrong?
    (i) Single N–N bond is stronger than the single P–P bond.
    (ii) PH₃ can act as a ligand in the formation of coordination compound with transition elements.
    (iii) NO₂ is paramagnetic in nature.
    (iv) Covalency of nitrogen in N₂O₅ is four.
15. A brown ring is formed in the ring test for NO₃^– ion. It is due to the formation of
    (i) [Fe(H₂O)₅ (NO)]²⁺
    (ii) FeSO₄.NO₂
    (iii) [Fe(H₂O)₄(NO)₂]²⁺
    (iv) FeSO₄.HNO₃
16. Elements of group-15 form compounds in +5 oxidation state. However, bismuth forms only one well characterised compound in +5 oxidation state. The compound is
    (i) Bi₂O₅
    (ii) BiF₅
    (iii) BiCl₅
    (iv) Bi₂S₅
17. On heating ammonium dichromate and barium azide separately we get
    (i) N₂ in both cases
    (ii) N₂ with ammonium dichromate and NO with barium azide
    (iii) N₂O with ammonium dichromate and N₂ with barium azide
    (iv) N₂O with ammonium dichromate and NO₂ with barium azide
18. In the preparation of HNO₃, we get NO gas by catalytic oxidation of ammonia. The moles of NO produced by the oxidation of two moles of NH₃ will be ______.
    (i) 2
    (ii) 3
    (iii) 4
    (iv) 6
19. The oxidation state of central atom in the anion of compound NaH₂PO₂ will be ______.
    (i) +3
    (ii) +5
    (iii) +1
    (iv) –3
20. Which of the following is not tetrahedral in shape?
    (i) NH₄⁺
    (ii) SiCl₄
    (iii) SF₄
    (iv) SO₄^2–
21. Which of the following are per oxoacids of sulphur?
    (i) H₂SO₅ and H₂S₂O₈
    (ii) H₂SO₅ and H₂S₂O₇
    (iii) H₂S₂O₇ and H₂S₂O₈
    (iv) H₂S₂O₆ and H₂S₂O₇
22. Hot conc. H₂SO₄ acts as moderately strong oxidising agent. It oxidises both metals and nonmetals. Which of the following element is oxidised by conc. H₂SO₄ into two gaseous products?
    (i) Cu
    (ii) S
    (iii) C
    (iv) Zn
23. A black compound of manganese reacts with a halogen acid to give greenish yellow gas. When excess of this gas reacts with NH₃ an unstable trihalide is formed. In this process the oxidation state of nitrogen changes from _________.
    (i) – 3 to +3
    (ii) – 3 to 0
    (iii) – 3 to +5
    (iv) 0 to – 3
24. In the preparation of compounds of Xe, Bartlett had taken O₂⁺ Pt F₆^– as a base compound. This is because
    (i) both O₂ and Xe have same size.
    (ii) both O₂ and Xe have same electron gain enthalpy.
    (iii) both O₂ and Xe have almost same ionisation enthalpy.
    (iv) both Xe and O₂ are gases.
25. In solid state PCl₅ is a _________.
    (i) covalent solid
    (ii) octahedral structure
    (iii) ionic solid with [PCl₆]⁺ octahedral and [PCl₄]^– tetrahedra
    (iv) ionic solid with [PCl₄]⁺ tetrahedral and [PCl₆]^– octahedra
26. Reduction potentials of some ions are given below. Arrange them in decreasing order of oxidising power.
    
27. Which of the following is isoelectronic pair?
    (i) ICl₂, ClO₂
    (ii) BrO₂^– , BrF₂⁺
    (iii) ClO₂, BrF
    (iv) CN^–, O₃

Multiple Choice Questions (Type-II)

Note : In the following questions two or more options may be correct.

1. If chlorine gas is passed through hot NaOH solution, two changes are observed in the oxidation number of chlorine during the reaction. These are ________ and _________.
   (i) 0 to +5
   (ii) 0 to +3
   (iii) 0 to –1
   (iv) 0 to +1
2. Which of the following options are not in accordance with the property mentioned against them?
   
3. Which of the following is correct for P₄ molecule of white phosphorus?
   (i) It has 6 lone pairs of electrons.
   (ii) It has six P–P single bonds.
   (iii) It has three P–P single bonds.
   (iv) It has four lone pairs of electrons.
4. Which of the following statements are correct?
   (i) Among halogens, radius ratio between iodine and fluorine is maximum.
   (ii) Leaving F—F bond, all halogens have weaker X—X bond than X—X’ bond in interhalogens.
   (iii) Among interhalogen compounds maximum number of atoms are present in iodine fluoride.
   (iv) Interhalogen compounds are more reactive than halogen compounds.
5. Which of the following statements are correct for SO₂ gas?
   (i) It acts as bleaching agent in moist conditions.
   (ii) It’s molecule has linear geometry.
   (iii) It’s dilute solution is used as disinfectant.
   (iv) It can be prepared by the reaction of dilute H₂SO₄ with metal sulphide.
6. Which of the following statements are correct?
   (i) All the three N—O bond lengths in HNO₃ are equal.
   (ii) All P—Cl bond lengths in PCl₅ molecule in gaseous state are equal.
   (iii) P₄ molecule in white phosphorus have angular strain therefore white phosphorus is very reactive.
   (iv) PCl is ionic in solid state in which cation is tetrahedral and anion is octahedral.
7. Which of the following orders are correct as per the properties mentioned against each?
   
8. Which of the following statements are correct?
   (i) S–S bond is present in H₂S₂O₆.
   (ii) In peroxo sulphuric acid (H₂SO₅) sulphur is in +6 oxidation state.
   (iii) Iron powder along with Al₂O₃ and K₂O is used as a catalyst in the preparation of NH₃ by Haber’s process.
   (iv) Change in enthalpy is positive for the preparation of SO3 by catalytic oxidation of SO₂.
9. In which of the following reactions conc. H2SO4 is used as an oxidising reagent?
   (i) CaF₂ + H₂SO₄ → CaSO₄ + 2HF
   (ii) 2HI + H2SO4 → I2 + SO2 + 2H2O
   (iii) Cu + 2H₂SO₄ → CuSO₄ + SO₂ + 2H₂O
   (iv) NaCl + H₂SO₄ → NaHSO₄ + HCl
10. Which of the following statements are true?
    (i) Only type of interactions between particles of noble gases are due to weak dispersion forces.
    (ii) Ionisation enthalpy of molecular oxygen is very close to that of xenon.
    (iii) Hydrolysis of XeF₆ is a redox reaction.
    (iv) Xenon fluorides are not reactive.

Short Answer Type Questions

1. In the preparation of H₂SO₄ by Contact Process, why is SO₃ not absorbed directly in water to form H₂SO₄?
2. Write a balanced chemical equation for the reaction showing catalytic oxidation of NH₃ by atmospheric oxygen.
3. Write the structure of pyrophosphoric acid.
4. PH₃ forms bubbles when passed slowly in water but NH₃ dissolves. Explain why?
5. In PCl₅, phosphorus is in sp³d hybridised state but all its five bonds are not equivalent. Justify your answer with reason.
6. Why is nitric oxide paramagnetic in gaseous state but the solid obtained on cooling it is diamagnetic?
7. Give reason to explain why ClF₃ exists but FCl₃ does not exist.
8. Out of H₂O and H₂S, which one has higher bond angle and why?
9. SF₆ is known but SCl₆ is not. Why?
10. On reaction with Cl₂, phosphorus forms two types of halides ‘A’ and ‘B’. Halide A is yellowish-white powder but halide ‘B’ is colourless oily liquid. Identify A and B and write the formulas of their hydrolysis products.
11. In the ring test of NO₃^– ion, Fe²⁺ ion reduces nitrate ion to nitric oxide, which combines with Fe²⁺ (aq) ion to form brown complex. Write the reactions involved in the formation of brown ring.
12. Explain why the stability of oxyacids of chlorine increases in the order given below: HClO < HClO₂ < HClO₃ < HClO₄
13. Explain why ozone is thermodynamically less stable than oxygen.
14. P₄O₆ reacts with water according to equation P₄O₆ + 6H₂O → 4H₃PO₃. Calculate the volume of 0.1 M NaOH solution required to neutralise the acid formed by dissolving 1.1 g of P₄O₆ in H₂O.
15. White phosphorus reacts with chlorine and the product hydrolyses in the presence of water. Calculate the mass of HCl obtained by the hydrolysis of the product formed by the reaction of 62 g of white phosphorus with chlorine in the presence of water.
16. Name three oxoacids of nitrogen. Write the disproportionation reaction of that oxoacid of nitrogen in which nitrogen is in +3 oxidation state.
17. Nitric acid forms an oxide of nitrogen on reaction with P₄O₁₀. Write the reaction involved. Also write the resonating structures of the oxide of nitrogen formed.
18. Phosphorus has three allotropic forms — (i) white phosphorus (ii) red phosphorus and (iii) black phosphorus. Write the difference between white and red phosphorus on the basis of their structure and reactivity.
19. Give an example to show the effect of concentration of nitric acid on the formation of oxidation product.
20. PCl₅ reacts with finely divided silver on heating and a white silver salt is obtained, which dissolves on adding excess aqueous NH₃ solution. Write the reactions involved to explain what happens.
21. Phosphorus forms a number of oxoacids. Out of these oxoacids phosphinic acid has strong reducing property. Write its structure and also write a reaction showing its reducing behaviour.

Matching Type Questions

Note : Match the items of Column I and Column II in the following questions.

1. Match the compounds given in Column I with the hybridisation and shape given in Column II and mark the correct option.
   
2. Match the formulas of oxides given in Column I with the type of oxide given in Column II and mark the correct option.
   
3. Match the items of Columns I and II and mark the correct option.
   
4. Match the species given in Column I with the shape given in Column II and mark the correct option.
   
5. Match the items of Columns I and II and mark the correct option.
   

Assertion and Reason Type Questions

Note : In the following questions a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices.
(i) Both assertion and reason are correct statements, and reason is the correct explanation of the assertion.
(ii) Both assertion and reason are correct statements, but reason is not the correct explanation of the assertion.
(iii) Assertion is correct, but reason is wrong statement.
(iv) Assertion is wrong but reason is correct statement.
(v) Both assertion and reason are wrong statements.

1. Assertion : N₂ is less reactive than P₄.
   Reason : Nitrogen has more electron gain enthalpy than phosphorus.
2. Assertion : HNO₃ makes iron passive.
   Reason : HNO₃ forms a protective layer of ferric nitrate on the surface of iron.
3. Assertion : HI cannot be prepared by the reaction of KI with concentrated H₂SO₄
   Reason : HI has lowest H–X bond strength among halogen acids.
4. Assertion : Both rhombic and monoclinic sulphur exist as S₈ but oxygen exists as O₂.
   Reason : Oxygen forms pπ – pπ multiple bond due to small size and small bond length but pπ – pπ bonding is not possible in sulphur.
5. Assertion : NaCl reacts with concentrated H₂SO₄ to give colourless fumes with pungent smell. But on adding MnO₂ the fumes become greenish yellow.
   Reason : MnO₂ oxidises HCl to chlorine gas which is greenish yellow.
6. Assertion : SF₆ cannot be hydrolysed but SF₄ can be.
   Reason : Six F atoms in SF₆ prevent the attack of H₂O on sulphur atom of SF₆.

Long Answer Type Questions

1. An amorphous solid “A” burns in air to form a gas “B” which turns lime water milky. The gas is also produced as a by-product during roasting of sulphide ore. This gas decolourises acidified aqueous KMnO₄ solution and reduces Fe³⁺ to Fe²⁺. Identify the solid “A” and the gas “B” and write the reactions involved.
2. On heating lead (II) nitrate gives a brown gas “A”. The gas “A” on cooling changes to colourless solid “B”. Solid “B” on heating with NO changes to a blue solid ‘C’. Identify ‘A’, ‘B’ and ‘C’ and also write reactions involved and draw the structures of ‘B’ and ‘C’.
3. On heating compound (A) gives a gas (B) which is a constituent of air. This gas when treated with 3 mol of hydrogen (H₂) in the presence of a catalyst gives another gas (C) which is basic in nature. Gas C on further oxidation in moist condition gives a compound (D) which is a part of acid rain. Identify compounds (A) to (D) and also give necessary equations of all the steps involved.

Answers

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