Indicate the number of unpaired electrons in: (a) P, (b) Si, (c) Cr, (d) Fe and (e) Kr.
(a) Phosphorus (P): 1s2 2s2 2p6 3s2 3p3
No of unpaired electron = 3
(b) Silicon (Si): 1s2 2s2 2p6 3s2 3p2
No of unpaired electron = 2 (since p orbital can have maximum 6 electron )
(c) Chromium (Cr): 1s2 2s2 2p6 3s2 3p6 4s1 3d5
No of unpaired electrons = 6 (since 1 electron is to be added to 4s & 5 electron to be added to 3d orbital.
(d) Iron (Fe): 1s2 2s2 2p6 3s2 3p6 4s2 3d6
No of unpaired electrons = 4
(e) Krypton (Kr): 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
Since all orbitals are fully occupied, there are no unpaired electrons in krypton.
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 wavelength of an electron moving with a velocity of 2.05 × 107 ms–1.
Using s, p, d notations, describe the orbital with the following quantum numbers.
(a) n = 1, l = 0;
(b) n = 3; l =1
(c) n = 4; l = 2;
(d) n = 4; l =3.
Which of the following are isoelectronic species i.e., those having the same number of electrons?
Na+, K+, Mg2+, Ca2+, S2–, Ar
Calculate the wavelength, frequency and wave number of a light wave whose period is 2.0 × 10–10 s.
How many electrons in an atom may have the following quantum numbers?
(a) n = 4,
(b) n = 3, l = 0
Yellow light emitted from a sodium lamp has a wavelength (λ) of 580 nm. Calculate the frequency (ν) and wave number () of the yellow light.
Calculate the wave number for the longest wavelength transition in the Balmer series of atomic hydrogen.
A photon of wavelength 4 × 10–7 m strikes on metal surface, the work function of the metal being 2.13 eV. Calculate
(i) the energy of the photon (eV),
(ii) the kinetic energy of the emission, and
(iii) the velocity of the photoelectron (1 eV= 1.6020 × 10–19 J).
Find energy of each of the photons which
(i) correspond to light of frequency 3× 1015 Hz.
(ii) have wavelength of 0.50 Å.
How do you account for the formation of ethane during chlorination of methane?
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
What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C?
What are the common physical and chemical features of alkali metals?
Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4
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
What is the basic theme of organisation in the periodic table?
Explain the formation of a chemical bond.
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.
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?
Calculate the hydrogen ion concentration in the following biological fluids whose pH are given below:
(a) Human muscle-fluid, 6.83
(b) Human stomach fluid, 1.2
(c) Human blood, 7.38
(d) Human saliva, 6.4.
It has been found that the pH of a 0.01M solution of an organic acid is 4.15. Calculate the concentration of the anion, the ionization constant of the acid and its pKa.
Fluorine reacts with ice and results in the change:
H2O(s) + F2(g) → HF(g) + HOF(g)
Justify that this reaction is a redox reaction.
The hydroxides and carbonates of sodium and potassium are easily soluble in water while the corresponding salts of magnesium and calcium are sparingly soluble in water. Explain.
Why is a solution of potassium hydroxide used to absorb carbon dioxide evolved during the estimation of carbon present in an organic compound?
Discuss the principle of estimation of halogens, sulphur and phosphorus present in an organic compound.
What will be the conjugate bases for the Brönsted acids: HF, H2SO4 and HCO3?
What does atomic radius and ionic radius really mean to you?
Draw the resonance structures for the following compounds. Show the electron shift using curved-arrow notation.
(a) C6H5OH
(b) C6H5NO2
(c) CH3CH=CHCHO
(d) C6H5–CHO
(e) C6 H5 - C+H2
(f) CH3CH = CHC+H2
Explain structures of diborane and boric acid.
It is very good trick. But my question is that. What amount of cyclohexane will contain same number of bond as the number of unpaired electron in 16.42liter o Oxygen gas measured as 1.2 atmospheric pressure and 27°c