Tiêu đề DPP-8 SOLUTION.pdf ✅

CLASS : XIth SUBJECT : CHEMISTRY DATE : DPP No. : 8 1 (b) Find λ from E = hc λ ; It comes out to be 4965 Å, which represents visible region (i.e., in between 3800 ― 7600 Å). 2 (a) The ground state configuration of chromium is 24Cr = [Ar]3d 5 4s 1 ∴ 24cr 2+ = [Ar]3d 4 4s 0 3 (b) The atomic number of cesium is 55. The electronic configuration of cesium atom is 55Cs = 1s 2 ,2s 2 2p 6 ,3s 2 3p 6 ,4s 2 ,3d104p 6 ,5s 2 ,4d 10,5p 6 ,6s 1 The electronic configuration of cesium atom is Cs + = 1s 2 ,2s 2 2p 6 ,3s 2 3p 6 3d 10,4s 2 4p 6 4d 10,5s 2 5p 6 ,6s 0 So, the total number of s-electrons =10, The total number of p-electrons=24, The total number of d-electrons=20 4 (c) KE = (1/2)mu 2 = eV ∴ u = 2eV m 5 (b) Sine, E ∝ ― 1 n 2 The energy of an electron in the second orbit will be E2 = E1 4 = ( ― 2.18 × 10―18J) 4 = ―5.45 × 10―19J 6 (b) Velocity of an electron in first orbit of H atom is u = 2.1847 × 108 1 cms ―1 Hence, it is 1 100th as compared to the velocity of light. 7 (c) Topic :- STRUCTURE OF ATOM Solutions
Energy values are always additive. Etotal = E1 + E2 hc λ = hc λ1 + hc λ2 1 λ = 1 λ1 + 1 λ2 1 355 = 1 680 + 1 λ2 λ2 = 742.77 nm ≈ 743 nm 8 (d) Bohr′s model is against the law of electrodynamics. 9 (b) Fe 3+ ion has the following configuration Fe 3+ = 1s 2 ,2s 2 2p 6 ,3s 2 3p 6 3d 5 Hence, ferric ion is quite stable due to half-filled d-orbitals. 10 (c) During the experimental verification of de Broglie equation, Davission and Germer confirmed wave nature of electron. For a given shell, say n = 2,l = 0 ∴ m = 0 l = 1 ∴ m = ―1, 0, + 1 11 (c) Anode rays particles are ionised gaseous atoms left after removal of electron. 12 (c) P has 5 valence electron; each H has 1; Thus, total electrons = 5 + 4 ― 1 = 8. 13 (b) Neutron is composed of +1p 1 + ―1e 0 and thus, net charge is zero. 14 (c) Picture tube of TV set is cathode rays tube. 15 (d) s-subshell has only one orbital and that is spherical, hence, s-orbitals are non-directional. 16 (b) 28Ni = 1s 2 ,2s 2 ,2p 6 ,3s 2 ,3p 6 ,4s 2 ,3d 8 Ni 2+ = 1s 2 ,2s 2 ,2p 6 ,3s 2 ,3p 6 ,3d 8 E 1 E 2 E
17 (d) In 1H 3 , nucleons are 3. 19 (a) m can be +2, +1 and 0 for 3d-subshell. 20 (c) For Paschen series, n1 = 3 and n2 = 4, 5, 6 two unpaired electrons
ANSWER-KEY Q. 1 2 3 4 5 6 7 8 9 10 A. B A B C B B C D B C Q. 11 12 13 14 15 16 17 18 19 20 A. C C B C D B D A A C