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A radioactive nuclide A decays to nuclide B which further decays to C. Their disintegration constant are λ1 and λ2 respectively. At t = 0 only nuclei A are present. Number of nuclei A at t = 0 is N0.
An enclosure filled with helium is heated to a temperature of 400 K. Helium atom emerges out of the enclosure. The mean debroglie wavelength of the helium atoms is :
When a metallic surface is illuminated with monochromatic light of wavelength λ, the stopping potential is 5 V0. When the same surface is illuminated with light of wavelength 3λ, the stopping potential is V0. Then the work function of the metallic surface is :
No. of identical photons incident on a perfectly black body of mass m kept at rest on smooth horizontal surface. Then the acceleration of the body if n number of photons incident per second is (Assume wavelength of photon to be λ) :
If we assume that penetrating power of any radiation/particle is inversely proportional to wavelength of the particle then :
Two radioactive sources A and B initially contain equal number of radioactive atoms. Source A has a half-life of 1 hour and source B has a half-life of 2 hours. At the end of 2 hours, the ratio of activity of source A to that of B is :
The radionuclide 238U decays by emitting an alpha particle.
What is the maximum kinetic energy of the emitted alpha particle? Express your answer in Joule.
(1amu =1.67 x 10-27 kg)
Choose the correct statement.
A beam of electrons striking a copper target produces X-rays.Its spectrum is as shown. Keeping the voltage same if the copper target is replaced with a different metal, the cut-off wavelength and characteristic lines of the new spectrum will change in comparision with old as :
Cut- off wavelength of emitted X-rays depends on maximum kinetic energy of incident electrons on the target and is independent of nature of target. The characteristic lines depend on nature of material of target.
Both the frequency and the intensity of a beam of light falling on the surface of photoelectric material are increased by a factor of two. This will :
The photon radiated from hydrogen corresponding to 2nd line of Lyman series is absorbed by a hydrogen like atom ‘X’ in 2nd excited state. As a result the hydrogen like atom ‘X’ makes a transition to nth orbit. Then,
The angular momentum of an electron in first orbit of Li++ ion is :
An electron is accelerated through a potential difference of V volt. It has a wavelength λassociated with it. Through what potential difference must an electron be accelerated so that its de-Broglie wavelength is the same as that of a proton? Take mass of a proton to be 1837 times larger than the mass of electron.
Two hydrogen atoms are in excited state with electrons residing in n = 2. First one is moving towards left and emits a photon of energy E1 towards right. Second one is moving towards left with same speed and emits a photon of energy E2 towards left. Taking recoil of nucleus into account during emission process
In a hydrogen atom following the Bohr’s postulates the product of linear momentum and angular momentum is proportional to (n)x where ‘n’ is the orbit number. Then ‘x’ is :
One of the lines in the emission spectrum of Li2+ has the same wavelength as that of the 2nd line of Balmer series in hydrogen spectrum. The electronic transition corresponding to this line is :
The ratio of wave length of a photon of energy E and deBroglie wavelength of an electron of mass 'm' having the kinetic energy also E is : (Speed of light = c)
An orbital electron in the ground state of hydrogen has an angular momentum L1 and an orbital electron in the first orbit in the ground state of lithium (double ionised positively charged) has an angular momentum L2 .Then :
If in the first orbit of a hydrogen atom the total energy of the electron is -21.76 x 10-19J, then its electric potential energy will be :
In an x - ray tube, if the accelerating potential difference is changed, then:
As the accelerating potential difference is changed only the minimum wavelength changes.
It has no effect on wavelengths of characteristic x-rays (whether they are produced or not)
All electrons ejected from a surface by incident light of wavelength 200 nm can be stopped before travelling 1 m in the direction of uniform electric field of 4 N/C. The work function of the surface is:
The energy ratio of two Kα photons obtained in x-ray from two metal targets of atomic numbers Z1 and Z2 is:
The energy of Kα x-ray photons is directly propotional to (z-1)2.The energy ration of two Kα photons obtained in x-ray from two metal targets of atomic number z1 and z2 is
A cobalt (atomic no. = 27) target is bombarded with electrons, and the wavelengths of its characteristic x-ray spectrum are measured. A second weak characteristic spectrum is also found, due to an impurity in the target. The wavelengths of the Kα lines are 225.0 pm (cobalt) and 100.0 pm (impurity). Atomic number of the impurity is (take b = 1)
In the photoelectric experiment, if we use a monochromatic light, the I - V curve is as shown. If work function of the metal is 2eV, estimate the power of light used. (Assume efficiency of photo emission = 10–3%, i.e. number of photoelectrons emitted are 10–3% of number of photons incident on metal.)
If first excitation potential of a hydrogen like atom is V volt, then the ionization energy of this atom will be :
The element which has a ka x-rays line of wavelength 1.8 Å is (R =1.1 x 107 m-1 , b=1 and = 0.39)
The radii of nuclei of two atoms are in ratio 3/2 . Assuming them to be Hydrogen like atom, the ratio of their orbital radius for K shell will be (assume no. of proton = No. of neutron for each atom)
A radioactive nucleus can decay by either emitting an α particle or by emitting a β particle. Probability of α decay is 75% while that of β decay is 25%. The decayconstant of α decay is λ1 and that of b decay is λ2 . is
A radioactive nucleus ' X ' decays to a stable nucleus ' Y '. Then the graph of rate of formation of ' Y' against time ' t ' will be :
Match column-I with column-II and select the correct answer using the codess given below :
Column-I (Metals) Column-II (Ores)
(a) Tin (p) Calamine
(b) Zinc (q) Cassiterite
(c) Iron (r) Cerrusite
(d) Lead (s) Siderite
(a) Tin-cassiterite,SnO2 (b)Zinc-calamine,ZnCO3 (c) Iron-siderite,FeCO3 (d)Lead-Cerrusite,PbCO3 Therefore ,(B) option is correct
Which is not a correct statement ?
Sulphide ore is roasted in presence of excess of air or O2 below its melting point to convert into the the oxide and to remove the impurities of S,P,Sb etc ,as their volatile oxides.In some cases roasting of certain sulphide ores provide directly the metals.
Which metal is extracted using a hydrometallurgical process involving complexation ?
Which of the following acids is monobasic?
ClO2 is the anhydride of :
As it gives mixture of two acids ,HClO2 and HClO3,it is called as mixed anhydride of HClO2 and HClO3. 2ClO2 + H2O→HClO2 + HClO3
.... is obtained when ammonium dichromate is heated.
In the Ostwald’s process, nitric acid is prepared by the catalytic oxidation of :
The thermal stability of hydrides of oxygen family is in order :
Down the group (H-E) bond dissociation enthalpy decreases as (H-E) bond length increases because of increase in size of cation.Thus thermal stability of hydrides also decreases.
Which of the following gaseous molecules is monoatomic ?
Noble gases exist as monoatomic molecules.
The transition elements have a general electronic configuration :
General electronic configuration of transition elements is [Noble gas]
The stable oxidation state of Cr is :
Cr3+ is most stable because in aqueous solution it has higher CFSE on account of half filled t32g energy level of 3d orbitals in octahedral spliting.
Which of the following ions gives colourless aqueous solution?
Cu+ is diamagnetic with 3d10 configuration; so no d-d transition is possible and thus colourless.
The developer used in photography is an alkaline solution of :
At 300ºC, FeCl3 :
What is the charge on the complex [Cr(C2O4)2(H2O)2] formed by Cr(III) ?
The correct IUPAC name for the compound [Co(NH3)4CI(ONO)]Cl is :
EAN of a metal carbonyl M(CO)x is 36. If atomic number of metal M is 26, what is the value of x ?
Which one of the following complexes produces three moles of silver chloride when its one mole is treated with excess of silver nitrate ?
(D) As 3 mole of Cl- are present outside the coordination sphere i.e. in ionisation sphere so according to the following reaction, 3Cl- + 3Ag+→3AgCl ,one mole of complex will give three moles of AgCl precipitate.
Which statement is incorrect ?
Which has maximum paramagnetic nature ?
contains maximum number of unpaired electrons i.e five.so it has the maximum paramagnetic character.
Which one of the following complexes has highest stability ?
It is a chelate complex having three five-membered rings.It attains extra stability through chelation.
[Co(NH3)5NO2]Cl2 and [Co(NH3)5ONO]Cl2 are related to each other as :
When a mixture of solid NaCl, solid K2Cr2O7 is heated with concentrated H2SO4, deep red vapours are obtained. This is due to the formation of :
Precipitate of PbSO4 is soluble in :
Nitrate is confirmed by ring test. The brown colour of the ring is due to formation of :
Nessler’s reagent is :
In which of the pair the precipitates are red and black coloured respectively and both are soluble in excess KI solution ?
(soluble colourless complex); (soluble orange complex).
The solution of sodium meta aluminate on diluting with water and then boiling with ammonium chloride gives:
Hydroxide ion concentration is reduced owing to the formation of ammonia(a weak base) which escapes on boiling.
Precipitate of Zn(OH)2 is soluble in :
If crimson flame is given when an inorganic mixture is tested by flame test. It may be due to the presence of
ABCD is a parallelogram and L and M are mid-points of BC and CD.Then
The angle between the planes 2x + y + 3z = 0 and 5x + 11y – 7z = 0 is
The graph of the equation y2 + z2 = 0 in three dimensional space is
Centroid of the tetrahedron OABC (where A = (a, 2, 3), B = (1, b, 2) , C = (2, 1 , c) and O is the origin) is (1, 2, 3) the value of a2 + b2 + c2 is equal to
If a plane meets co-ordinate axes in A, B, C such that the centroid of the triangle is (1, k, k2) then equation of the plane is
Matrix A is of m × (m + 5) type, matrix B is of n × (11 – n) type. If AB and BA exists then value of m + n is
If a1, a2, a3 ,.............,an all are real number with a1 0 and are in A.P then the system of equations has
If a square matrix A satisfies polynomial equation x3 – 5x2 + 4x + k = 0 , then A–1 exists if
The coefficient of a quadratic equation ax2 + bx + c = 0 (a, b and c are different) are chosen from first three prime number, the probability that roots of the equation are real is
First three prime numbers are (2,3,5) so they can be arranged in total 3! ways over three places, n(s)=3!.Roots are real only if (2,5,3) or (3,5,2) are the arrangements so,n(A)=2 P(A)=2/6=1/3
Two dice are rolled one after another. The probability that the number on the first is less than or equal to the number on the second is.
A boy is throwing stones at a target. The probability of hitting the target at any trial is 1/2 . The probability of hitting the target 5th time at the 10th throw is
In the 10th throw he hit 5th time if in first 9 throws he hit 4 times and miss 5 times and in 10th throw he hits so if H = Event of hitting then required probability will be
Consider the circuit If the probability that each switch is closed is P,then the probability of current flowing through AB is
The probability that a particular day in the month of July is a rainy day is 3/4. Two person whose credibility are 4/5 and 2/3respectively claim that 15th July was a rainy day. The probability that it is a rainy day.
If A and B are two events such that P(A) = 1/2 and P(B) = 2/3 , then
The co-ordinates of the point where the line joining P(3, 4, 1) and Q(5, 1, 6) crosses the xy-plane are
The direction ratios of a normal to the plane through (1, 0, 0), (0,1, 0), which makes an angle of π/4 with the plane x + y = 3 are :
The reflection of the point (2, –1, 3) in the plane 3x – 2y – z = 9 is :
The plane ax + by + cz = d, meets the coordinate axes at the points A, B and C respectively. Area of triangle ABC is equal to
Equation of plane which passes through the point of intersection of lines and and at greatest distance from the point (0, 0, 0) is: