Atomic Structure Questions and Answers

Let the mass of electron is two times mass o proton is 1 4th and mass of neutron is 3 2 a original mass Then the atomic weight of C atom 1 Increases by 37 5 2 Decreases by 87 5 3 Decreases by 12 5 4 Remains same

where dr is a small volume element The values of y which are in accordance with the above conditions are taken as valid and are known as Eigen functions and the values of E corresponding to valid values of u are called Eigen values The eigen function for an electron is called an atomic orbital Note As the eigen values are very nearly similar to energy levels of different Bohr s orbits the occurrence of definite energy levels in an atom follows directly from the wave mechanical concepts Significance of y The wave function may be regarded as the amplitude function expressed in terms of coordinates x y and z The wave function may have positive or negative

Which transition of electron in Li2 would emit the photon whose wavelength will be same as that of photon emitted by Hydrogen atoms corresponding to 2nd line of Balmer series Question Type Single Correct Type 16 12 284 38 2

of M 10 KIO3 the same stock solution of KI requires 30 mL of M KIO3 under similar conditions calculate the percenta AgNO3 in the sample Reaction KIO3 2KI 6HCl 31C1 3KC1 3H O IIT JEE 1 22 The composition of a sample of wustite is Feo 93 What percentage of iron is present in the form of Fe IIT JEE 23 A is a binary compound of a univalent metal When g of A reacts completely with 0 321 of sulphur evacuated and sealed tube 1 743 g of a white cryst solid B produces which produces a hydrated doub C with Al2 SO4 3 Identify A B and C IIT JEE g 24 A mixture of ethane CH ond othane CH occur

8h Ym dx The total energy of the particle is sum of kinetic energy and potential energy i e Thus or E K E P E E d y h 8 ym dx 2 y 8 h 2 dx m X P E E P E y 0 2 iv This equation is called Schr dinger wave equation in ne dimension x If it is written for a particle whose motion is escribed by three space coordinates x y and z then the above x y an values TH for the obser positi the E nega desc spac qua

32 Hydrogen peroxide solution 20 mL reacts quar with a solution of KMnO4 20 mL acidified w H SO4 The same volume of the KMnO4 soluti decolourised by 10 mL of MnSO4 in a neutral simultaneously forming a dark brown preci hydrated MnO The brown precipitate is dissol mL of 0 2 M sodium oxalate under boiling condit presence of dilute H SO4 Write the balanced involved in the reactions and calculate the m H O IT IF

200 units of energy is required to take away electron from the lowest energy level to infinity The energy released when electron falls from infinite level to the second shell Assuming Bohr model to be applicable will be Question Type Single Correct Type 1 100 units 2 400 units 3 50 units A 25 unito

Which of the following has been arranged in order of decreasing freezing point Question Type Single Correct Type 0 05 M KNO3 0 04 M CaCl 1 0 140 M sugar 0 075 M CuSO4 2 3 4 0 04 M BaCl 0 140 M sucrose 0 075 M CuSO4 0 05 M KNO3 0 075 M CuSO4 0 140 M sucrose 0 40 M BaCl 0 05 M KNO3 0 075 M CuSO4 0 05 M NaNO3 0 140 M sucrose 0 04 M ROCL

A sample of H atoms containing all the atoms is some excited state is irradiated with the light of wavelength and atoms get re excited to further higher excited state On removing the light source atoms de excite to the ground state with the emission of radiations The emission spectrum thus obtained consists of ten spectral lines Out of these ten spectral lines seven lines have wavelengths smaller and only two line have wavelengths longer than The orbit number for initial excited state is

on is moving in 3rd orbit of Li 2 and its separation energy is y The separation energy of an electron moving in 2nd orbit of Het is 13 62 2 1 4y 9 2 9 y 3 9 4 y

True or false If false explain clearly in complete sentences and with all arguments why is it false 1 The fifth excited energy level of a particle in a perfect cube a b c is not degenerate

210 The threshold frequency vo for a metal is 5 x 1014 s Calculate the kinetic energy of an electron emitted when the metal is irradiated with a radiation of frequency 2 x 10 5 Hz 2 twn experimental phenomena ukish M G groterand II 2

1 The energy of an electron in the second and third Bohr s orbits of a hydrogen atom are 5 41 x 10 erg and 2 41 x10 2 erg respectively The wavelength of emitted radiation when the electron drops from the third to the second orbit is x x 107 m The value of x is Use h 6 63 x 1034 Js 12 2 g of CH g at a certain temperature and pressure condition occupies 11 2 L If the pressure of the gas is

NA 2 A sample of H atoms having electrons in the ground state is exposed to high energy rays of quantum energy 13 3875 eV The H atoms absorb the energy and get excited When the electron drops from excited state to the ground state how many lines are seen in the emission spectrum of hydrogen

2 A sample of H atoms having electrons in the ground state is exposed to high energy rays of quantum energy 13 3875 eV The H atoms absorb the energy and get excited When the electron drops from excited state to the ground state how many lines are seen in the emission spectrum of hydrogen

46 An alpha particle and a proton are accelerated separately by the potential difference of 2 V and ZV respectively but ratio of de Broglie wavelength of alpha particle to proton is 2 The value of Z is

It is found that 3 125 x 108 g atoms of Rn exist in equilibrium with 1 g of radium at 0 C and 1 atm pressure The disintegration constant of Ra is 1 48 x 10 11 s Calculate the disintegration constant of Rn

35 17Cl and 37 17Cl are symbols of tw o isotopes of chlorine i Compare the atoms of these isotopes with respect to the composition of nuclei 2

or here 1 V RH 2 n V wave number 109677 76 cm 1 daglug V RH X C 1 1 2 n2 1 2 2 n n 2 where RH is Rydberg constant for hydrogen Its value is cm 01x0220 idho tel to For Balmer series n 2 and n2 3 4 5 6 the atom

A mixture of Li CO and Na CO is heated strongly in an open vessel If the loss in mass of mixture is Na 23 A 1 1 220 The molar ratio of Li CO and Na CO in the initial mixture is Li 7 9 B 1 2 C 2 1 D 11 4

Incorrect statement among the following is are a 1 g atom of oxygen is No times heavier than 1 atom of oxygen b 1 m of H g at STP weighs 89 2 g c Blue vitriol and green vitriol are isomorphous substances 1 a only 3 b only 2 b c only 4 c only

of all gases contain equal number of atoms at same temperature and pressure This statement is 1 In accordance with Dalton s atomic theory and is known as Berzelius Hypothesis 2 Not in accordance with Dalton s atomic theory and is known as Avogadro s Hypothesis 3 Not in accordance with Dalton s atomic theory and is known as Berzelius Hypothesis 4 In accordance with Dalton s atomic theory and is known as Avogadro s Hypothesis

nsition series spectrum Wavenumber 109677 1 n1 2 1 n2 2 Is n1 always smaller than n2 Cant this val ue be negative When the energy is absorb ed can this value be negative as the electro n is jumping from lower energy level to high er energy level

Five ionization energy values in kJ mol are listed below E 870 E 830 E3 1010 E4 1290 E5 376 These are a successive ionization energies for the element with atomic number 5 b the first I E of successive elements in group 15 16 17 18 and 1 respectively c the first I E of elements with atomic number 1 to 5 d successive I E for transition elements with four electrons in d subshell

1 a Write down the Planck distribution law for black body radiation in one convenient form and hence show that the wavelength corresponding to the maximum energy density is inversely proportional to the absolute temperature Assume hc AKRT 1 terms have their usual significancel

WBSU Year 2012 1 c Calculate the de Broglie wavelength for an electron me 9 1x10 31 kg having kinetic energy as 13 6 eV Given electronic charge 1 6 10 19 coulomb 3

2 3 Comprehension Type I Read the paragraph carefully and answer the following questions Due to very high speed of electrons in atoms molecules etc they show some relativistic effect fine structure of spectra being one of them We know that fine structure was sought to be explained earlier by assuming the spinning of electron about its own axis The quantum numbers now associated with the explanation are called spin quantum number s and magnetic spin quantum number ms for historical reasons only 1 The former is the analogue of for orbital motion but it is restricted to the single unchanged value of 1 2 The magnitude of the spin angular momentum is given by the expression S S 1 1 2 h so for an 2 2 The second quantum number the spin magnetic quantum number ms may take only two values 1 2 and 1 2 These quantum number specify the orientation of the spin with respect to a choosen axis and the component of spin angular momentum along an axis The spin is purely quantum mechanical property and differs considerably from its classical namesake Because the spin state of an electron must be specified if the state of the atom is to be specified fully It is common to say that the state of an electron in a hydrogenic atom is characterized by four quantum number n 1 m and ms the fifth quantum number s is fixed at 1 2 electron this magnitude is fixed at 1 2 h 31 12 The spin angular momentum of last electron of sodium atom is A 3 C 3 1 3h 4 D zero B Which of the following quantum number has not come from non relativistic Schrodinger wave equation A C s B m D n 1 The quantum number 1 2 and 1 2 for the electron spin represent A rotation of the electron in clock wise and anti clock wise direction respectively B rotation of the electron in anticlockwise and clock wise direction respectively C magnetic moment of the electron pointing up and down respectively D two quantum mechanical spin states which have no classical analogue

e What is photoelectric effect Draw a plot of kinetic energy for the ejected photoelectron vs frequency of the incident radiation in a photoelectric experiment with three different metals What inference regarding physical quantities may be drawn from the plot 1 3 4

25 Maximum number of electrons in a subshell of an atom is determined by the following a 2 1 b 4 2 c 2n d 4 2 2009 Which of the following is not permissible 31 Give Plan unce velo a

10 The uncertainty in momentum of an electron is 1 x 10 5 kg m s The uncertainty in its position will be h 6 62 10 34 kg m s a 5 27 10 30 m b 1 05 10 26 m d 5 25 x 10 28 c 1 05 x 10 28 m m 1999

A sample containting large number of Li2 ions all in a particular excited state is subjected a photons coming from M shell to K shell transition of any unielectronic species If the samp is further excited to a higher level de excites back to the ground state then calculate energ of the photon eV having 8th highest energy among all emitted from de excitation

44 The position of both an electron and a helium atom is known within 1 0 nm Further the momentum of the electron is known within 5 0 10 26 kg m s The minimum uncertainty in the measurement of the momentum of the helium atom is a 8 0 10 26 b 80 kg m s kg m s c 50 kg m s d 5 0 10 26 kg m s The ion that is igno 1998 52 53

c Hund d ommerfield 1999 42 The de Broglie wavelength of a particle with mass 1 g and velocity 100 m s is a 6 63 10 35 m c 6 63 10 33 m b 6 63 10 34 m d 6 65 10 35 m 1999 43 The Bohr orbit radius for the hydrogen atom number 3 a 0 53 c 0 17 50 For which o quantum num highest energ 1 2 n a 3

The value of n 1 2 3 4 and 5 for the Lyman Balmer Paschen Brackett and Pfund series respectively n2 is greater than n by at least 1 Values of n and n2 for various series Spectral series Value of n 1 2 Lyman series Balmer series Paschen series Brackett series Value of n 2 3 4 5 3 4 5 6 4 5 6 7 4 5 6 7 8 Pfund series 5 6 7 8 9 Lyman series is observed in both absorption and emission spectrum of hydrogen Series Limit Last line of a spectrum is called the series limit Last line is also called the line of shortest wavelength and highest energy We know 3 Total six lines in the s Mathematical formula n n Viewed Balmer lines by the naked eye n 3 Ha first line Red 6563 n 2 Illuant n 4 HB second line Blue 4861 A n 2 Fig 2 19 Balmer se

9 How many degenerate orbitals are present in a subshell if electron associated with that subshell possesses orbital angular momentum 2 3 1 No degenerate orbitals 2 Seven degenerate orbitals 3 Three degenerate orbitals 4 number of degenerate orbitals are same as in subshell which possesses u 3 46 B M wher colle to s two Ch

What volume of a liquid in L will contain 10 mole If molar mass of liquid density is 1 4g mL 16 g of SO gas occupies 5 6L at 1 atm and 273 K What will be the value of 200 mL of 1M HCl is mixed with 300 mL of 6 M HCl and the final solution 1000 mL Calculate molar concentration of H ion w boots N g reacts with H g in either of the following ways depending upon supp

show hamiltonian operator for the plane waves exponential imaginary Prove that this operator does not change this function Prove that this operator does generate energy of a particle in free space

3 31 pm then minimum uncertainty in kinetic energy is yx10 16 J Calculate the value of y TI 13 In a sample of excited hydrogen atoms electrons make transition from n 2 to n 1 Emitted quanta strike on a metal of work function 4 2eV Calculate the wavelength in associated with ejected electrons having maximum kinetic energy 14 For 1s orbital of Hydrogen atom radial wave function is given as 3 2 R r e r ao where a 0 529 1 1 ao The ratio of radial probability density of finding electron at r a to the radial probability density of finding electron at the nucleus is given as x e Calculate the value of x y 15 Calculate the value of A A E1 2 2E21 Sjeve I where Enz Energy of electron in nth orbit Z atomic number of hydrogen like

Imagine a alternate existing universe in which the set of 4 quantum numbers exist in given values n 1 to infinity 0 to n 1 m l 1 to l 1 including zero S 1 2 0 1 2 On the basis of given data in which periodic table s block copper will belong and what would be its electronic config uration in ground stato 2

7 Which transition emits photon of maximum frequenc 1 2nd spectral line of Balmer series 2 2nd spectral line of Paschen series 3 5th spectral line of Humphery series 4 Ist spectral line of Lymen series

Describe the motion of a charged particle in uniform magnetic field In a chamber a uniform magnetic field of 6 5G is maintained An electron is shot into the field with a speed of 4 8x106ms normal to the field Determine the radius of the circular orbit e 1 6x10 C M 9 1x10 Kg

The mass of a dust particle is 10 2 g and its velocity is 104 cm sec The error in the measurement of velocity is 0 01 The uncertainty in the measurement of h position in unit is 4T 0 527 x 10 2 27 ergsec

13 An oxide of nitrogen has a molecular weight 92 Find the total number of electrons in one gram mole of that oxide 1 4 6N 2 46N 3 23N 4 2 3N 14 Total number of species present in 1 mole of notash alum in terms of avagadro number N

Kn 28 Balmer gave an equation for wavelength of visible region of H spectrum as 2 4 Where n principal quantum number of energy level K constant in terms of R Rydberg constant The value of K in terms of R is R a R b 2 4 R d 5 R IG 1

o felectron 9 10 kg ty of light 3 x 10 ms 1 s constant 6 626 x 10 34 Js of electron 1 6 10 19 jeV 1 0 9eV 3 1eV 2 1eV 2 1eV 21791 581 hc 1 2mv 2 34 6 626 X10 X 3X10 2 x 9 1X103 X 6 105 X 4000 X1070 32995804 what is the work fuction of the metal if the light of wavelength 4000 generates photoelectrons of velocity 6 105 ms from JEE Mains 2019 12 January Shift 1 it 31 Mass o felectron 9 10 kg Velocity of light 3 108ms 1 Planck s constant 6 626 10 34 Js Charge of electron 1 6 10 19 je V 1 1 2 d doubtnu 62801 Watch Later What will be the workings of the metal if 4000 AWavelength light 6 105 m Produces photoelectrons of velocity 1 31 1 34 Electron code 9 10 kg velocity of light 3 10 ms Planck constant 6 626 X 10 Js and the charge of electron 1 6 x 10 1 JeV 000

m 1 d 2 a 4 1 1 How ma d 4p 6 tron which is rem 0 ms 1 173 Wave function of an orbital is plotted against the distance from nucleus The graphical representation is of a 1s b 2s R c 3s d 2p

174 The Schrodinger wave equation for hydrogen atom is 3 2 1 1 4 25 ao 4 2 o where ao is Bohr s radius If the radial node in 2s be at ro then ro would be equ ao d ao b 2a0 c 2 ao a 2 Je r ao

Element A has 5 isotopes Out of every 220 A atoms 11 atoms have a mass of 176 u 41 8 atoms have a mass of 177 u 59 4 atoms have a mass of 178 u and the other two have a mass of 179 u and 180 u The relative atomic mass of X is 178 49 Calculate the percentage abundance of A 179 and 178 A Write the nuclide symbol of the most abundant isotope of this element

The reaction N O5 in CC14 solution 2NO2 solution 0 g 2 is of first order in N O5 with rate constant 6 2 10 s What is the value of rate of reaction when N O5 1 25 mol L A 7 75 x 10 mol L s B 6 35 10 mol L s C 5 15 x 10 5 mol L s D 3 85 x 10 mol L s

1 8 and 1 2 25 and 1 3 2 and 4 The energy of an electron in first Bohr orbit of H atom is 13 6 eV The energy value of electron in the excited JEE MAINS ONLINE 2014 state of Li2 is 4 30 6 eV 1 30 6 eV 2 27 2 eV 1813 3 27 2 eV