if , then will be infinite (d) Problem 5: Number of nodal planes (planes of zero electron density) in the orbital is (a) 1 (b) 2 (c) 0 (d) 4 Solution: xz and yz are planes with zero electron density for orbital. (b) Problem 6: If the speed of electron in the Bohr’s first orbit of hydrogen atom is x the speed of the electron in the third Bohr’s orbit is (a) x/9 (b) x/3 (c) 3x (d) 9x Solution: According to Bohr’s model for hydrogen and hydrogen like atoms the velocity of an electron in an atom is quantized and is given by (b) Problem 7: The quantum numbers of most energetic electron in Ne atom when it is in first excited state is (a) 2, 1, 0, 1/2 (b) 3, 1, 1, ½ (c) 3, 0, 0, 1/2 (d) 3, 1, 0, 1/2. Solution: The electronic configuration of Ne atom is . In its first excitation state the electron from 2p will unpair and shift to 3s where its quantum numbers will be 3, 0, 0, ½. (c) Problem 8: Which set of quantum number is not consistent with the quantum mechanical theory? (a) n = 2, l = 1, m = 1, s = ½ (b) n = 4, l = 3, m = 2, s = –1/2 (c) n = 3, l = 2, m = 3, s = +1/2 (d) n = 4, l = 3, m = 3, s = +1/2. Solution: The e is a well defined co-relation between n, l, m and s quantum numbers in an atom. l = (n 1), m will be ½, for n = 3 cannot be m = 3. Highest – value m will be 2. (c) Problem 10: Of the following transitions in hydrogen atom, the one gives an absorption line of lowest frequency is (a) n = 1 to n = 2 (b) n = 3 to n = 8 (c) n = 2 to n = 1 (d) n = 8 to n = 3
if , then will be infinite (d) Problem 5: Number of nodal planes (planes of zero electron density) in the orbital is (a) 1 (b) 2 (c) 0 (d) 4 Solution: xz and yz are planes with zero electron density for orbital. (b) Problem 6: If the speed of electron in the Bohr’s first orbit of hydrogen atom is x the speed of the electron in the third Bohr’s orbit is (a) x/9 (b) x/3 (c) 3x (d) 9x Solution: According to Bohr’s model for hydrogen and hydrogen like atoms the velocity of an electron in an atom is quantized and is given by (b) Problem 7: The quantum numbers of most energetic electron in Ne atom when it is in first excited state is (a) 2, 1, 0, 1/2 (b) 3, 1, 1, ½ (c) 3, 0, 0, 1/2 (d) 3, 1, 0, 1/2. Solution: The electronic configuration of Ne atom is . In its first excitation state the electron from 2p will unpair and shift to 3s where its quantum numbers will be 3, 0, 0, ½. (c) Problem 8: Which set of quantum number is not consistent with the quantum mechanical theory? (a) n = 2, l = 1, m = 1, s = ½ (b) n = 4, l = 3, m = 2, s = –1/2 (c) n = 3, l = 2, m = 3, s = +1/2 (d) n = 4, l = 3, m = 3, s = +1/2. Solution: The e is a well defined co-relation between n, l, m and s quantum numbers in an atom. l = (n – 1), m will be ½, for n = 3 cannot be m = 3. Highest value m will be 2. (c) Problem 10: Of the following transitions in hydrogen atom, the one gives an absorption line of lowest frequency is (a) n = 1 to n = 2 (b) n = 3 to n = 8 (c) n = 2 to n = 1 (d) n = 8 to n = 3
ATOMIC-STRUCTURE.docx