Class 11 Chemistry The p Block Elements: NCERT Solutions for Question 30
A certain salt X, gives the following results.
(i) Its aqueous solution is alkaline to litmus.
(ii) It swells up to a glassy material Yon strong heating.
(iii) When conc. H2SO4 is added to a hot solution of X, white crystal of an acid Z separates out.
Write equations for all the above reactions and identify X, Y and Z.
The given salt is alkaline to litmus. Therefore, Xis a salt of a strong base and a weak acid. Also, when Xis strongly heated, it swells to form substance Y. Therefore, Xmust be borax.
When borax is heated, it loses water and swells to form sodium metaborate. When heating is continued, it solidifies to form a glassy material Y. Hence, Ymust be a mixture of sodium metaborate and boric anhydride.
More Questions From Class 11 Chemistry - Chapter The p Block Elements
- Q:-
What happens when
(a) Borax is heated strongly,
(b) Boric acid is added to water,
(c) Aluminium is treated with dilute NaOH,
(d) BF3 is reacted with ammonia?
- Q:-
Give reasons:
(i) Conc. HNO3 can be transported in aluminium container.
(ii) A mixture of dilute NaOH and aluminium pieces is used to open drain.
(iii) Graphite is used as lubricant.
(iv) Diamond is used as an abrasive.
(v) Aluminium alloys are used to make aircraft body.
(vi) Aluminium utensils should not be kept in water overnight.
(vii) Aluminium wire is used to make transmission cables.
- Q:-
Write reactions to justify amphoteric nature of aluminium.
- Q:-
Why does boron trifluoride behave as a Lewis acid?
- Q:-
Discuss the pattern of variation in the oxidation states of
(i) B to Tl and (ii) C to Pb. - Q:-
Write balanced equations for:
(i) BF3 + LiH →
(ii) B2H6 + H2O →
(iii) NaH + B2H6 →
(iv) H3BO3
(v) Al + NaOH →
(vi) B2H6 + NH3 →
- Q:-
How can you explain higher stability of BCl3 as compared to TlCl3?
- Q:-
(a) Classify following oxides as neutral, acidic, basic or amphoteric:
CO, B2O3, SiO2, CO2, Al2O3, PbO2, Tl2O3
(b) Write suitable chemical equations to show their nature.
- Q:-
Rationalise the given statements and give chemical reactions :
(i) Lead(II) chloride reacts with Cl2 to give PbCl4.
(ii) Lead(IV) chloride is highly unstable towards heat.
(iii) Lead is known not to form an iodide, PbI4.
- Q:-
An aqueous solution of borax is
(a) neutral (b) amphoteric (c) basic (d) acidic
Popular Questions of Class 11 Chemistry
- Q:-
How do you account for the formation of ethane during chlorination of methane?
- Q:-
What are hybridisation states of each carbon atom in the following compounds ?
(i) CH2=C=O,
(ii) CH3CH=CH2,
(iii) (CH3)2CO,
(iv) CH2=CHCN,
(v) C6H6
- Q:-
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
- Q:-
What are the common physical and chemical features of alkali metals?
- Q:-
Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4 - Q:-
Assign oxidation number to the underlined elements in each of the following species:
(a) NaH2PO4
(b) NaHSO4
(c) H4P2O7
(d) K2MnO4
(e) CaO2
(f) NaBH4
(g) H2S2O7
(h) KAl(SO4)2.12 H2O
- Q:-
What is the basic theme of organisation in the periodic table?
- Q:-
Explain the formation of a chemical bond.
- Q:-
Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only. - Q:-
A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?
Recently Viewed Questions of Class 11 Chemistry
- Q:-
How much time would it take to distribute one Avogadro number of wheat grains, if 1010 grains are distributed each second?
- Q:-
Kp = 0.04 atm at 899 K for the equilibrium shown below. What is the equilibrium concentration of C2H6 when it is placed in a flask at 4.0 atm pressure and allowed to come to equilibrium?
C2H6 (g) ↔ C2H4 (g) + H2 (g)
- Q:-
Predict which of the following reaction will have appreciable concentration of reactants and products:
a) Cl2 (g) ↔ 2Cl (g) Kc = 5 ×10–39
b) Cl2 (g) + 2NO (g) ↔ 2NOCl (g) Kc = 3.7 × 108
c) Cl2 (g) + 2NO2 (g) ↔ 2NO2Cl (g) Kc = 1.8
- Q:-
Energy of an electron in the ground state of the hydrogen atom is –2.18 × 10–18 J. Calculate the ionization enthalpy of atomic hydrogen in terms of J mol–1.
- Q:-
An ion with mass number 56 contains 3 units of positive charge and 30.4% more neutrons than electrons. Assign the symbol to this ion.
- Q:-
Calculate the number of kJ of heat necessary to raise the temperature of 60.0 g of aluminium from 35°C to 55°C. Molar heat capacity of Al is 24 J mol–1 K–1.
- Q:-
What is the basic theme of organisation in the periodic table?
- Q:-
Do you expect different products in solution when aluminium(III) chloride and potassium chloride treated separately with
(i) normal water
(ii) acidified water, and
(iii) alkaline water?
Write equations wherever necessary.
- Q:-
Arrange the following set of compounds in order of their decreasing relative reactivity with an electrophile, E+
(a) Chlorobenzene, 2,4-dinitrochlorobenzene, p-nitrochlorobenzene
(b) Toluene, p-H3C-C6H4-NO2, p-O2N-C6H4-NO2.
- Q:-
For an isolated system, ΔU = 0, what will be ΔS?
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