Chemistry

The p-Block Elements.

Question:

What inspired N. Bartlett for carrying out reaction between Xe and PtF6?

Answer:

N. Bartlett observed that PtF6 reacts with O2to give an compound O2+ [PtF6].
PtF6 (g) + O2 (g) ——–>O2+[PtF6]
Since the first ionization enthalpy of Xe (1170 kJ  mol-1  )is fairly close to that of 02 molecule (1175 kJ mol-1 ), he thought that PtF6  should also oxidise Xe to Xe+. This inspired Bartlett to carryout the reaction between Xe and PtF6. When PtF6 and Xe were made to react, a rapid reaction took place and a red solid, Xe+[PtF6] was obtained.
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The p-Block Elements.

Q 1.

How is O3 estimated quantitatively?

Q 2.

Name three oxoacids of nitrogen. Write the disproportionation reaction of that oxoacid of nitrogen in which nitrogen is in +3 oxidation state.

Q 3.

 How is nitrogen prepared in the laboratory? Write the chemical equations of the reactions . involved.

Q 4.

Discuss the trends in chemical reactivity of group 15 elements.

Q 5.

Match the items of Column I and Column II and mark the correct option.
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Q 6.

Explain why inspite of nearly the same electronegativity, nitrogen forms hydrogen bonding while chlorine does not.

Q 7.

Explain why does the stability of oxoacids of chlorine increase in the order given below:
HClO < HClO2 < HClO3 < HClO4

Q 8.

Match the compounds given in Column I with the hybridization and shape given in Column II and mark the correct option.
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Q 9.

 Why is BiH3 the strongest reducing agent amongst all the hydrides of group 15 elements? (C.B.S.E. 2013)

Q 10.

Give two examples to show the anomalous behaviour of fluorine.

Q 11.

 Why does nitrogen show catenation properties less than phosphorus ? (C.B.S.E. Foreign 2009)

Q 12.

Why is BiH3 the strongest reducing agent amongst all the hydrides of Group 15 elements?

Q 13.

Write main differences between the properties of white phosphorus and red phosphorus.

Q 14.

Why does nitrogen show catenation properties less than phosphorus?

Q 15.

Explain why fluorine forms only one oxoacid, HOF.

Q 16.

Assertion (A): HNO3 makes from passive.
Reason (R): HNO3 forms a protective layer of ferric nitrate on the surface of iron.

Q 17.

 Why is N2 less reactive at room temperature?

Q 18.

 What is the covalence of nitrogen in N2O5 ?

Q 19.

Complete the following reactions:
(i)C2H2 + O2 -> (ii) 4Al + 3 O2 ->

Q 20.

Write the conditions to maximise the yield of H2SO4 by Contact process.

Q 21.

Why has it been difficult to study the chemistry of radon?

Q 22.

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.

Q 23.

Explain why fluorine forms only one oxoacid, HOF.

Q 24.

 How are XeOand XeOF4prepared?

Q 25.

Bond angle in PH4+ is higher than that in PH3. Why?

Q 26.

Write a balanced equation for the hydrolytic reaction of PC is in heavy water.

Q 27.

What happens when sulp'hur dioxide is passed through an aqueous solution of Fe(III) salt?

Q 28.

Can PCl5 act as an oxidising as well as a reducing agent Justify.

Q 29.

Write a balanced chemical equation, for the reaction showing catalytic oxidation of NH3 by atmospheric oxygen.

Q 30.

Out of H2O and H2S, which one has higher bond angle and why?

Q 31.

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.

Q 32.

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.

Q 33.

An amorphous solid "A"bums 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 Fe+2. Identify the solid "A"and the gas "B"and write the reactions involved.

Q 34.

 What happens when white phosphorus is heated with concentrated NaOH solution in an inert atmosphere of CO2?

Q 35.

What happens when sulp’hur dioxide is passed through an aqueous solution of Fe(III) salt?

Q 36.

Mention three areas in which H2SO4 plays an important role.

Q 37.

The HNH angle value is higher than HPH, H AsH and HSbH angles. Why?
(Hint: Can be explained on the basis of sp3 hybridisation in NH3 and only s-p bonding , between hydrogen and other elements of the group).

Q 38.

Explain why NH3 is basic while BiH3 is only feebly basic.

Q 39.

Why is dioxygen a gas but sulphur a solid?

Q 40.

 Why do noble gases have comparatively large atomic size?

Q 41.

 List the uses of neoirand argon gases.

Q 42.

Why is N2 less reactive at room temperature?

Q 43.

What happens when H3PO4 is heated?

Q 44.

How is O3 estimated quantitatively?

Q 45.

Why does the reactivity of nitrogen differ from phosphorus?

Q 46.

Why does R3P = O exist but R3N = O does not (R = alkyl group)?

Q 47.

Nitrogen exists as diatomic molecule and phosphorus as P4. Why?

Q 48.

Give the formula and describe the structure of a noble gas species which is isostructural with:  (i) ICI4 (ii) IBr2 (iii) Br03

Q 49.

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
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Q 50.

In a cyclotrimeta phosphoric acid molecule, how many single and double bonds are present? .
(a) 3 double bonds; 9 single bonds
(b) 6 double bonds; 6 single bonds
(c) 3 double bonds; 12 single bonds
(d) Zero double bonds; 12 single bonds