Description : What is Aufbau’s principle? How it helps to fill electrons in an atom in different orbitals?
Last Answer : Ans Electrons are filled in orbitals of an atom according to increasing energies which is in accordance to (n+l) values of electrons. If (n+l )values are same the electron goes to orbital having lower value of n.
Description : “In reality all the s-orbitals are spherically symmetric.” What does this represent?
Last Answer : Ans. The probable density of an electron in s-orbital is equally distributed at all coordinates in space.
Description : Tell what would happen to the stability of an atom, with atomic number higher than18, if the aufbau principle was not introduced.
Last Answer : Ans. We cannot find out the exact reason of stability of an atom & why they should have filled inner orbits before outermost shell.
Description : What accounts for the stability of an electron in multi-electron atom?
Last Answer : Ans. i.The angular momentum of an electron is integral multiple of h/2ח ii. The symmetrical electron density of an orbit. iii.The maximum transition energy of an orbital.
Description : Explain the significance of spin quantum number.
Last Answer : Ans.The direction of spinning of an electron in an orbit as well as the net magnetic moment of an orbital.
Description : Explain the significance of Azimuthal quantum number.
Last Answer : Ans. It refers as sub-energy level of an atom.
Description : Write two properties which cannot be explain by wave nature of radiation
Last Answer : Ans. 1.Photo electric effect 2. Black Body radiation
Description : What do you mean by Pauli’e exclusive principle? What is its significance?
Last Answer : Ans No two electrons will have same set of all q.no. If n,l,m are same i.e. same orbital ‘s’ will be differ. It shows that all electrons have a definite place in an atom or their own identity.
Description : What is Hund’s rule of maximum multiplicity? What is its significance?
Last Answer : Ans Pairing of electrons in an orbital takes place only when all orbitals of same sub-shell become singly occupied. It helps to equalize energy of a sub-shell
Description : How many of the following are possible: 1p, 2s, 3p, 3f, 3d.
Last Answer : Ans.2s , 3p & 3d are possible.
Description : How many quantum numbers are needed to designate an orbital?
Last Answer : Ans.Three quantum numbers.
Description : Is the energy of an electron in 2s orbital same as of that in 2p orbital? Why?
Last Answer : Ans. No, the energy depends upon (n+l) values in an atom. Hence 2p orbital has greater energy than 2s.
Description : Why is s-orbital orbital considered non directional while p-orbital directional?
Last Answer : Ans. Electron density in s-orbital is equal in all direction while it dumble shaped along one axis in p- orbitals.
Description : Find the number of radial and angular nodes in 3d subshell?
Last Answer : Ans. Zero-angular node as well as radial nodes.
Description : How many maximum 3s electrons can have magnetic spin quantum number -1/2?
Last Answer : Ans. 1 electrons.
Description : What are different types of quantum numbers , write them with their symbols ?
Last Answer : Ans. 1.Principal Quantum Numbers (n) 2.Azimuthal Quantum Numbers(l) 3.Magnetic Quantum Numbers (m) 4.Spin Quantum Numbers(s)
Description : Define Pauli’s exclusion principle ?
Last Answer : Ans. No two electrons in an atom can have same set ofall four quantum numbers. If three are same one Quantum number must have different value.
Description : Give the points of Rutherford Model.
Last Answer : Ans. 1. Atom is neutral. 2.Whole mass is concentrated in nucleus. 3.Electrons are revolving in orbits.
Description : Write the draw back of Rutherford Atomic Model.
Last Answer : Ans (1). He was unable to explain the stability of Atom. (2). He could not explain the line spectrum.
Description : Why; e/m value is not constant for canal rays ?
Last Answer : Ans. Mass of particles of cathode rays is not constant.
Description : What is threshold frequency?
Last Answer : Ans –The minimum frequency required to eject out electron from an atom.
Description : Name the spectral series which appear in the region of electromagnetic spectrum. (a) Visible region (b) UV region (c) Far IR region
Last Answer : Ans: (a) Balmer Series (b) Lymen Series (c) Pfund Series
Description : What is the difference between Quantum and photon?
Last Answer : Ans. The smallest packet of Energy of any radiation is called as Quantum and that of Light is known as Photon.
Description : State Heisenberg Uncertainty Principle.
Last Answer : Ans. It is impossible to determine the exact position & exact momentum or velocity of microscopic particle.
Description : The number of `pi` molecular orbitals completely filled in the ground state of benzene is :
Last Answer : The number of `pi` molecular orbitals completely filled in the ground state of benzene is : A. three B. one C. six D. none
Description : Which of the following complex ions has electrons that are symmetrically filled in both `t_(2g) and e_(g)` orbitals ?
Last Answer : Which of the following complex ions has electrons that are symmetrically filled in both `t_(2g) and e_(g)` orbitals ? A ... D. `[Co(NH_(3))_(6)]^(2+)`
Description : When do d orbitals start to get filled?
Last Answer : Need answer
Description : Which of the following is incorrect? (a) Resonance stabilization is the extra stability a compound gains from having delocalized electrons. (b) Delocalized electrons destabilize a compound. (c) The greater ... stable resonance contributors, the greater is the resonance stabilization. (d) (a) and (c)
Last Answer : Delocalized electrons destabilize a compound
Description : A characteristic of the noble gases is that they all: w) have eight electrons in the outer shell x) have low stability y) form many compounds z) have filled outer electron shells
Last Answer : ANSWER: Z -- HAVE FILLED OUTER ELECTRON SHELLS
Description : In the method of voids for determination of the quantity of cement paste, it is assumed that (A) Voids in coarse aggregates are filled by fine aggregates (B) Voids in fine aggregates are filled by ... of fine aggregates is equal to total voids in coarse aggregates plus 10% extra (D) All the above
Last Answer : Answer: Option D
Description : Ionisation energy of nitrogen is greater than that of oxygen because nitrogen has – (1) high bond dissociation energy (2) smaller atomic radius (3) stable half filled 2p sub level (4) high nuclear charge
Last Answer : (3) stable half filled 2p sub level Explanation: Ionization energy is a measure of the ease in which atoms lose electrons and become positive ions.
Description : Ionisation energy of nitrogen is greater than that of oxygen because nitrogen has (1) high bond dissociation energy (2) smaller atomic radius (3) stable half filled 2p sub level (4) high nuclear charge
Last Answer : stable half filled 2p sub level
Description : Compare the following complexes’ with respect to structural shapes of units, magnetic behaviour and hybrid orbitals involved in units : (i) [Ni(CN)4]2- (ii) [NiCl4]2- (iii) [CoF6]3- [At. Nos. : Ni = 28; Co = 27] -Chemistry
Last Answer : (i) [Ni(CN)4]2- Shape : Octahedral outer orbital complex Hybridisation : sp3d2 Magnetic behaviour : Paramagnetic (4 unpaired electrons)
Description : Compare the following complexes with respect to structural shapes of units, magnetic behaviour and hybrid orbitals involved in units : [Co(NH3)6]+3, [Cr(NH3)6]3+, Ni(CO)4 (At. nos. : Co = 27, Cr = 24, Ni = 28) -Chemistry
Last Answer : (i) [Co(NH3)6]+3 → Octahedral shape, d2sp3 hybridisation, diamagnetic Formation of [Co(NH2)6]+3 → oxidation state of Co is +3.
Description : Compare the following complexes with respect to their shape, magnetic behaviour and the hybrid orbitals involved : (i) [CoF4]2- (ii) [Cr(H2O)2(C2O4)2]– (iii) [Ni(CO)4] (Atomic number : Co = 27, Cr = 24, Ni = 28) -Chemistry
Last Answer : (i) [COF4]2_ : Tetrafluorido cobalt (III) ion Coordination number = 4 Shape = Tetrahedral Hybridisation = sp3 Important Questions for Class 12 Chemistry Chapter 9 Coordination Compounds Class 12 Important Questions 7
Description : For the complex [Fe(en)2Cl2], Cl, (en = ethylene diamine), identify (i) the oxidation number of iron, (ii) the hybrid orbitals and the shape of the complex, (iii) the magnetic behaviour of the complex, (iv) ... an optical isomer also, and (vi) name of the complex. (At. no. of Fe = 26) \ -Chemistry
Last Answer : i) [Fe(en)2Cl2] Cl or x + 0 + 2 (-1) + (-1) = 0 x + (- 3) = 0 or x = + 3 ∴ Oxidation number of iron, x = + 3 (ii) The complex has two bidentate ligands and two ... )2Cl2] Cl, only cis-isomer shows optical isomerism. (vi) Name of complex: Dichloridobis (ethane-1, 2- diamine) Iron (III) chloride
Description : The high reactivity of fluorine is due to (1) small size of fluorine atom (2) its high electro negativity (3) availability of d-orbitals (4) strong F - F bond
Last Answer : (2) its high electro negativity Explanation: The high reactivity of fluorine is due to its high electro negativity.
Description : Give conditions for the combination of Atomic Orbitals
Last Answer : Ans i).The combining atomic orbitals must have the same or nearly the same energy ii).The combining atomic orbitals must have the same symmetry about the molecular axis iii) The combining atomic orbitals must overlap to the maximum extent
Description : The delocalized π system in benzene is formed by a cyclic overlap of 6 orbitals. (a) s (b) p (c) sp (d) sp2
Last Answer : p
Description : The N–H bond in the ammonium ion, NH4+, is formed by the overlap of what two orbitals? (a) sp3–sp3 (b) sp3–sp2 (c) sp2–sp2 (d) sp3–s
Last Answer : sp3–s
Description : Where are the two lone pairs of electrons of the oxygen atom in an alcohol molecule located? (a) in two p orbitals (b) in two sp orbitals (c) in two sp2 orbitals (d) in two sp3 orbitals
Last Answer : in two sp3 orbitals
Description : What two atomic orbitals or hybrid atomic orbitals overlap to form the carbon-carbon σ bond in ethyne? (a) sp3–sp3 (b) sp2–sp2 (c) s–s (d) sp–sp
Last Answer : sp–sp
Description : The bond angles associated with the hybrid orbitals of a carbon involved in a triple bond is (a) 180° (b) 120° (c) 109° (d) 45
Last Answer : 180
Description : What orbitals overlap to create the H–C bond in CH3+? (a) sp3–sp3 (b) sp2–sp3 (c) s–p (d) s–sp2
Last Answer : s–sp2
Description : Which of the following statements is correct regarding nucleophiles? (a) They have an overall positive charge (b) They have a lone-pair of electrons (c) They have an unpaired electron (d) They have empty orbitals
Last Answer : (b) They have a lone-pair of electrons
Description : What is bond angle between the hybrid orbitals in methane? (a) 180° (b) 120° (c) 109.5° (d) 115.5°
Last Answer : 109.5°
Description : Compound in which carbons use only sp3 hybrid orbitals for bond formation is (a) CH3CH2CH3 (b) CH3C≡CH (c) CH3CH=CH2 (d) CH2=CH—CH=CH2
Last Answer : CH3CH2CH3
Description : The catalytic activity of transition metals and their compounds is ascribed mainly to (1) their chemical reactivity (2) their magnetic behaviour (3) their unfilled d-orbitals (4) their ability to adopt variable oxidation states
Last Answer : (4) their ability to adopt variable oxidation states
Description : The order of energy level of molecular orbitals in H3 species in a. 1σ < 2σ = 3σ b. 1σ >2σ = 3σ c. 1σ =2σ < 3σ d. 1σ < 2σ < 3σ
Last Answer : d. 1σ < 2σ < 3σ
Description : The nuclei of heavy atoms generally contain: w) more electrons than neutrons x) more protons than electrons y) more neutrons than electrons z) more orbitals than electrons
Last Answer : ANSWER: Y -- MORE NEUTRONS THAN ELECTRONS