Ncert class 11- chemistry- unit 2-Structure of Atom Welcome to your Ncert class 11- chemistry- unit 2-Structure of Atom 1. 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; $$r_{n} = (53^{2})pm$$ 1.33 nm 1.20 nm 1.50 nm None None 2. Any 𝑛𝑓− orbital can accommodate upto:- Six electrons Two electrons with opposite spin Two electrons with parallel spin 14 electron None 3. The Bohr radius of the fifth electron of phosphorus (atomic number = 15) acting as dopant in silicon (relative dielectric constant = 12) is 0.53𝐴º 21.2𝐴º 10.6 𝐴º None of these None 4. Which of the following radiations has largest energy ? 𝜆 = 30nm $$𝑣 = 3 × 10 ^{12}$$ 𝜆 = 300pm $$𝑣 = 3 × 10 ^{10}$$ None 5. Bohr's theory can be applied to determine the? first ionization energy of Be atom second ionization energy of helium atom Electronegativity of 𝐿𝑖2+ ion electron gain enthalpy of hydrogen atom None 6. The velocity of the electron in 3rd orbit of hydrogen atom in \( cms^{-1}\) $$2.44× 10^{12}$$ $$4.88 × 10^{4}$$ $$2.44 × 10^{8}$$ $$7.29 × 10^{7}$$ 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. $$\frac{3q}{ 4 \varepsilon _{0}h }$$ $$\frac{3q^{2}}{2\varepsilon _{0}h }$$ $$\frac{3q^{2}}{ 4 \varepsilon _{0}h }$$ $$\frac{3q}{ 2 \varepsilon _{0}h }$$ None 8. Which of the following hydrogen bonds are strongest in vapour phase?𝐻F......𝐻I 𝐻𝐹......𝐻Cl 𝐻F......𝐻I 𝐻𝐹......𝐻𝐹 𝐻Cl......𝐻Cl None 9. 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 Z<X<Y Y<Z<X 𝑋<𝑌<𝑍 𝑍 < 𝑌 < 𝑋 None 10. 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 11. Identify the incorrect statement among the following: 4 𝑓 and 5 𝑓 orbitals are equally shielded 𝐿 𝑎 La and 𝐿 𝑢 Lu have partially filled d-orbitals and no other partially filled orbitals. d-Block elements show irregular and erractic chemical properties among themselves. The chemistry of various lanthanoids is very similar. None 12. 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? $$Li^{+}$$ $$B$$ $$Be^{+}$$ $$Be^{2+}$$ None 13. 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).$$𝑣_{𝑛} = C/n^{2}$$ $$𝑣_{𝑛} = C × n^{2}$$ $$𝑣_{𝑛} = C/n$$ $$𝑣_{𝑛} = C × n$$ $$𝑣_{𝑛} = C/n^{2}$$ None 14. Which one of the following is considered as the main postulate of Bohr's model of atom Angular momentum of electron is an integral multiple of h/2π 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 None 15. Which principle/ rule limits the maximum number of electrons in orbital to two? Pauli's exclusion principle Hund's rule of maximum multiplicity Heisenberg's uncertainty principle Aufbau principle None 16. 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 𝑣 < 𝑖 𝑖 < 𝑖 𝑖 𝑖 < 𝑖 iv<ii<iii<i 𝑖 𝑖 𝑖 < 𝑖 < 𝑖 𝑣 < 𝑖 𝑖 𝑖 𝑖 < 𝑖 𝑣 < 𝑖 𝑖 < 𝑖 None 17. A trend common to both group 𝐼I and 𝑉𝐼𝐼VII elements in the periodic table as atomic number increase is Oxidising power increase Maximum valency increase Reactivity with water increase Atomic radius increase None 18. Ratio of series limit of Brackett and Pfund series of hydrogen ato spectrum is 4/9 1/4 9/16 16/25 None 19. 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 three atoms cant say. two atoms None 20. Which of the atomic number represents s -block elements? 9, 17 7, 15 3, 12 6, 12 None 21. Atomic number of 𝑁 is 7. The atomic number of 3rd member of nitrogen family is 23 43 15 33 None 22. 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: 2nd line of Balmer series of this sample has same energy value as 1st excitation energy of H-atom 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 Atomic number of element is 4. 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.
