Compare the relative stability of the following species and indicate their magnetic properties:
O2,O2+,O2- (superoxide), O22-(peroxide)
The stability of following species can be decided on the basis of bond order as follows:
O2 : KK
Bond order =1/2(Nb-Na)
= 1/2(8-4)
= 2 = Paramagnetic
Similarly, the electronic configuration of O2+ can be written as:
Bond order of O2+ = 1/2(8-3)
= 2.5 = paramagnetic
Electronic configuration of O2- ion will be:
Bond order of = 1/2(8-5)
= 1.5 = paramagnetic
Electronic configuration of O22- ion will be:
Bond order of O22- =1/2(8-6) = 1 diamagnetic
The larger the bond order,greater is the stability
Therefore the stability decreases as O2+ > O2 > O2- > O22-.
The mass of an electron is 9.1 × 10–31 kg. If its K.E. is 3.0 × 10–25 J, calculate its wavelength.
Calculate the amount of carbon dioxide that could be produced when
(i) 1 mole of carbon is burnt in air.
(ii) 1 mole of carbon is burnt in 16 g of dioxygen.
(iii) 2 moles of carbon are burnt in 16 g of dioxygen.
Calculate the wavelength of an electron moving with a velocity of 2.05 × 107 ms–1.
Balance the following redox reactions by ion – electron method :
(a) MnO4 – (aq) + I – (aq) → MnO2 (s) + I2(s) (in basic medium)
(b) MnO4 – (aq) + SO2 (g) → Mn2+ (aq) + HSO4– (aq) (in acidic solution)
(c) H2O2 (aq) + Fe 2+ (aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
(d) Cr2O7 2– + SO2(g) → Cr3+ (aq) + SO42– (aq) (in acidic solution)
In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
In a reaction A + B2 → AB2 Identify the limiting reagent, if any, in the following reaction mixtures.
(i) 300 atoms of A + 200 molecules of B
(ii) 2 mol A + 3 mol B
(iii) 100 atoms of A + 100 molecules of B
(iv) 5 mol A + 2.5 mol B
(v) 2.5 mol A + 5 mol B
At 0°C, the density of a certain oxide of a gas at 2 bar is same as that of dinitrogen at 5 bar. What is the molecular mass of the oxide?
Which one of the following will have largest number of atoms?
(i) 1 g Au (s)
(ii) 1 g Na (s)
(iii) 1 g Li (s)
(iv) 1 g of Cl2(g)
Density of a gas is found to be 5.46 g/dm3 at 27 °C at 2 bar pressure. What will be its density at STP?
Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?
Density of a gas is found to be 5.46 g/dm3 at 27 °C at 2 bar pressure. What will be its density at STP?
What causes the temporary and permanent hardness of water?
Among NH3, H2O and HF, which would you expect to have highest magnitude of hydrogen bonding and why?
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?
Balance the following redox reactions by ion – electron method :
(a) MnO4 – (aq) + I – (aq) → MnO2 (s) + I2(s) (in basic medium)
(b) MnO4 – (aq) + SO2 (g) → Mn2+ (aq) + HSO4– (aq) (in acidic solution)
(c) H2O2 (aq) + Fe 2+ (aq) → Fe3+ (aq) + H2O (l) (in acidic solution)
(d) Cr2O7 2– + SO2(g) → Cr3+ (aq) + SO42– (aq) (in acidic solution)
An aqueous solution of borax is
(a) neutral (b) amphoteric (c) basic (d) acidic
Why is nitric acid added to sodium extract before adding silver nitrate for testing halogens?
Which of the following pairs of elements would have a more negative electron gain enthalpy?
(i) O or F
(ii) F or Cl
What is the state of hybridisation of carbon in
(a) CO2-3
(b) diamond
(c) graphite?
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How to identify para or dia magnet ic
WASTE
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