Ncert class 11- chemistry- unit 2-Structure of Atom Welcome to your Ncert class 11- chemistry- unit 2-Structure of Atom 1. Ratio of series limit of Brackett and Pfund series of hydrogen ato spectrum is 1/4 4/9 9/16 16/25 None 2. Find an expression for de Broglie wavelength for an electron in the 𝑛𝑡ℎn th orbit of the Bohr model of the hydrogen atom and hence find its value when the electron is in n = 4 level.Take radius of nth orbital of Bohr's model of H-atom; $$r_{n} = (53^{2})pm$$ 1.20 nm 1.33 nm None 1.50 nm None 3. In an atom the order of increasing energy of electrons with quantum numbers.i) n=4,l=1 ii) n=3,l=2 iii) n=3,l=1 iv) n=4,l=0 𝑖 𝑖 𝑖 < 𝑖 𝑣 < 𝑖 < 𝑖 𝑖 iii<iv<i<ii 𝑖 𝑖 𝑖 < 𝑖 < 𝑖 𝑣 < 𝑖 𝑖 𝑣 < 𝑖 𝑖 < 𝑖 𝑖 𝑖 < 𝑖 iv<ii<iii<i 𝑖 𝑖 𝑖 < 𝑖 𝑣 < 𝑖 𝑖 < 𝑖 None 4. Bohr's theory can be applied to determine the? Electronegativity of 𝐿𝑖2+ ion first ionization energy of Be atom electron gain enthalpy of hydrogen atom second ionization energy of helium atom None 5. Which one of the following is considered as the main postulate of Bohr's model of atom Centrifugal force produced due to the revolving electrons balances the force of attraction between electron and protons Protons are present in the nucleus Electrons are revolving around the nucleus Angular momentum of electron is an integral multiple of h/2π None 6. Mass numbers of Li, Be and B are 7, 9 and 10 respectively. Which of the following has two electrons, three protons and four neutrons? $$Li^{+}$$ $$Be^{+}$$ $$Be^{2+}$$ $$B$$ None 7. In a hypothetical system a particle of mass m and charge -3 q is moving around a very heavy particle having charge q. Assuming Bohr's model to be true to this system, the orbital velocity of mass m when it is nearest to heavy particle is. $$\frac{3q}{ 2 \varepsilon _{0}h }$$ $$\frac{3q}{ 4 \varepsilon _{0}h }$$ $$\frac{3q^{2}}{ 4 \varepsilon _{0}h }$$ $$\frac{3q^{2}}{2\varepsilon _{0}h }$$ None 8. Which of the following radiations has largest energy ? $$𝑣 = 3 × 10 ^{12}$$ 𝜆 = 30nm $$𝑣 = 3 × 10 ^{10}$$ 𝜆 = 300pm None 9. Three photons originating from exited atomic hydrogen atoms are found to have energies of 0.66 eV, 1.89 eV and 2.55 eV respectively. The minimum no. of atoms that must be present are : one atom two atoms three atoms cant say. None 10. Which of the atomic number represents s -block elements? 6, 12 9, 17 3, 12 7, 15 None 11. According to Bohr's theory of the hydrogen atom, the speed \(𝑣_{𝑛}\) of the electron in a stationary orbit is related to the principal quantum number n as (C is a constant).$$𝑣_{𝑛} = C/n^{2}$$ $$𝑣_{𝑛} = C/n$$ $$𝑣_{𝑛} = C/n^{2}$$ $$𝑣_{𝑛} = C × n^{2}$$ $$𝑣_{𝑛} = C × n$$ None 12. Any 𝑛𝑓− orbital can accommodate upto:- 14 electron Six electrons Two electrons with opposite spin Two electrons with parallel spin None 13. The velocity of the electron in 3rd orbit of hydrogen atom in \( cms^{-1}\) $$2.44 × 10^{8}$$ $$2.44× 10^{12}$$ $$7.29 × 10^{7}$$ $$4.88 × 10^{4}$$ None 14. The Bohr radius of the fifth electron of phosphorus (atomic number = 15) acting as dopant in silicon (relative dielectric constant = 12) is 21.2𝐴º 10.6 𝐴º None of these 0.53𝐴º None 15. Atomic number of 𝑁 is 7. The atomic number of 3rd member of nitrogen family is 23 33 43 15 None 16. Which principle/ rule limits the maximum number of electrons in orbital to two? Heisenberg's uncertainty principle Hund's rule of maximum multiplicity Pauli's exclusion principle Aufbau principle None 17. Identify the incorrect statement among the following: 4 𝑓 and 5 𝑓 orbitals are equally shielded d-Block elements show irregular and erractic chemical properties among themselves. 𝐿 𝑎 La and 𝐿 𝑢 Lu have partially filled d-orbitals and no other partially filled orbitals. The chemistry of various lanthanoids is very similar. None 18. Which of the following hydrogen bonds are strongest in vapour phase?𝐻F......𝐻I 𝐻𝐹......𝐻𝐹 𝐻𝐹......𝐻Cl 𝐻Cl......𝐻Cl 𝐻F......𝐻I None 19. A trend common to both group 𝐼I and 𝑉𝐼𝐼VII elements in the periodic table as atomic number increase is Atomic radius increase Maximum valency increase Reactivity with water increase Oxidising power increase None 20. In a hydrogen like sample electron is in 2nd excited state,the energy of the 4th state of this sample is -13.6 eV,then the incorrect statement is: Atomic number of element is 4. 3 different types of spectral lines will be observed if electrons make transition upto ground state from the 2nd excited state. A 25 eV photon can set free the electron from the 2nd excited state of this sample 2nd line of Balmer series of this sample has same energy value as 1st excitation energy of H-atom None 21. Containers X, Y and Z of the equal volume contain oxygen, neon and methane respectively at the same temperature and pressure. The correct increasing order of their masses is:Z<X<Y Y<Z<X Z<X<Y 𝑋<𝑌<𝑍 𝑍 < 𝑌 < 𝑋 None 22. For a nucleus to be stable, the correct relation between neutron number N and proton number Z is N<Z N>Z 𝑁 ⩾ 𝑍 N=z None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to commentEnter your email address to commentEnter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
