Chemistry NCERT Exemplar Solutions Class 12th Chapter Seven

Assertion : HNO₃ makes iron passive. 

Reason : HNO₃ forms a protective layer of ferric nitrate on the surface of iron.

(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.

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.

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

Which of the following statements are correct? 

(i) S–S bond is present in H₂S₂O₆. 

(ii) In peroxosulphuric acid H₂SO₄ 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.

Which of the following orders are correct as per the properties mentioned against each? 

(i) As₂O₃ < SiO₂ < P₂O₃ < SO₂               Acid strength. 

(ii) AsH₃ < PH₃ < NH₃                             Enthalpy of vapourisation. 

(iii) S< O < Cl <  F                                    More negative electron gain enthalpy. 

(iv) H₂O  > H₂S  > H₂Se  > H₂Te             Thermal stability.

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.

Which of the following statements are correct for SO₂ gas? 

(i) It acts as a 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.

Which of the following statements are correct? 

(i) Among halogens, the radius ratio between iodine and fluorine is maximum. 

(ii) Leaving the F—F bond, all halogens have weaker X—X bonds than X—X'bonds in interhalogens. 

(iii) Among interhalogen compounds maximum number of atoms are present in iodine fluoride. 

(iv) Interhalogen compounds are more reactive than halogen compounds.

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.