Practice Questions

Q29.From the given transfer characteristic of a transistor in CE configuration, the value of power gain of this configuration is 10x , for RB = 10 kΩ, and RC = 1 kΩ. The value of x is _____. JEE Main 2023 (13 Apr Shift 1) JEE Main Previous Year Paper

Q29.In a medium the speed of light wave decreases to 0 . 2 times to its speed in free space. The ratio of relative permittivity to the refractive index of the medium is 𝑥: 1. The value of 𝑥 is ______. (Given speed of light in free space = 3 × 108 m s-1 and for the given medium 𝜇𝑟= 1)

Q29.A bi convex lens of focal length 10 cm is cut in two identical parts along a plane perpendicular to the principal axis. The power of each lens after cut is _____ D.

Q30.When two resistance R1 and R2 connected in series and introduced into the left gap of a meter bridge and a resistance of 10 Ω is introduced into the right gap, a null point is found at 60 cm from left side. When R1 and R2 are connected in parallel and introduced into the left gap, a resistance of 3 Ω is introduced into the right- gap to get null point at 40 cm from left end. The product of R1 R2 is ______ Ω2

Q30.If 917 Å be the lowest wavelength of Lyman series then the lowest wavelength of Balmer series will be Å.

Q30.In a metre bridge experiment the balance point is obtained if the gaps are closed by 2 Ω and 3 Ω. A shunt of X Ω is added to 3 Ω resistor to shift the balancing point by 22. 5 cm. The value of X is ______.

Q30.As per given figure A, B and C are the first, second and third excited energy levels of hydrogen atom n will be e. λ2 respectively. If the ratio of the two wavelengths (i. λ1 ) is 4n7 , then the value of

Q30.In a screw gauge, there are 100 divisions on the circular scale and the main scale moves by 0 . 5 mm on a complete rotation of the circular scale. The zero of circular scale lies 6 divisions below the line of graduation when two studs are brought in contact with each other. When a wire is placed between the studs, 4 linear scale divisions are clearly visible while 46th division the circular scale coincide with the reference line. The diameter of the wire is ______ × 10-2 mm .

Q30.For hydrogen atom, 𝜆1 and 𝜆2 are the wavelengths corresponding to the transitions 1 and 2 respectively as 𝑥 shown in figure. The ratio of 𝜆1 and 𝜆2 is 32. The value of 𝑥 is ______.

Q30.A monochromatic light is incident on a hydrogen sample in ground state. Hydrogen atoms absorb a fraction of light and subsequently emit radiation of six different wavelengths. The frequency of incident light is 𝑥× 1015 Hz. The value of x is ________ (Given ℎ= 4 . 25 × 10-15 eVs) Q31.25 mL of silver nitrate solution ( 1M ) is added dropwise to 25 mL of potassium iodide ( 1 . 05 M ) solution. The ion(s) present in very small quantity in the solution is/are (1) I- only (2) K+only (3) NO3- only (4) Ag+ and I-both

Q30.Assume that protons and neutrons have equal masses. Mass of a nucleon is 1 . 6 × 10-27 kg and radius of 1 nucleus is 1 . 5 × 10-15 A 3 m. The approximate ratio of the nuclear density and water density is n × 1013. The value of n is _____.

Q30.A light of energy 12 . 75 eV is incident on a hydrogen atom in its ground state. The atom absorbs the radiation and reaches to one of its excited states. The angular momentum of the atom in the excited state is 𝑥 – 15 – 𝜋× 10-17 eVs. The value of 𝑥 is ______ (use ℎ= 4 . 14 × 10 eVs, 𝑐= 3 × 108 m s 1)

Q30.The decay constant for a radioactive nuclide is 1 . 5 × 10-5 s-1. Atomic weight of the substance is 60 g mole-1, 𝑁𝐴= 6 × 1023. The activity of 1 . 0 µ g of the substance is ________ × 1010 Bq.

Q31.An organic compound gives 0. 220 g of CO2 and 0. 126 g of H2O on complete combustion. If the % of carbon is 24 then the % of hydrogen is _________ × 10–1. (Nearest integer)

Q31.Number of hydrogen atoms per molecule of a hydrocarbon A having 85. 8% carbon is (Given : Molar mass of A = 84 g mol−1 )

Q31.The molality of a 10%(v/V) solution of di-bromine solution in CCl4 (carbon tetrachloride) is x '. x = _____ × 10−2M. (Nearest integer) [Given : molar mass of Br2 = 160 g mol−1 atomic mass of C = 12 g mol−1 atomic mass of Cl = 35. 5 g mol−1 density of dibromine = 3. 2 g cm−3 density of CCl4 = 1. 6 g cm−3]

Q32.Assume carbon burns according to following equation : 2C(s) + O2( g) →2 CO (s) when 12 g carbon is burnt in 48 g of oxygen, the volume of carbon monoxide produced is ______ × 10−1 L at STP [nearest integer] [Given : Assume CO as ideal gas, Mass of C is 12 g mol−1 , mass of O is 16 g mol−1 and molar volume of an idal gas at STP is 22. 7 L mol−1 ]

Q32.The volume of hydrogen liberated at STP by treating 2. 4 g of magnesium with excess of hydrochloric acid is ...... ×10−2 L. Given Molar volume of gas is 22. 4 L at STP. Molar mass of magnesium is 24 g mol−1

Q32.The number of following statement/s which is/are incorrect is ______ A) Line emission spectra are used to study the electronic structure B) The emission spectra of atoms in the gas phase show a continuous spread of wavelength from red to violet. C) An absorption spectrum is like the photographic negative of an emission spectrum D) The element helium was discovered in the sun by spectroscopic method

Q33.The number of correct statements from the following is ........... A. For 1s orbital, the probability density is maximum at the nucleus B. For 2s orbital, the probability density first increases to maximum and then decreases sharply to zero. C. Boundary surface diagrams of the orbitals encloses a region of 100% probability of finding the electron. D. p and d -orbitals have 1 and 2 angular nodes respectively E. probability density of p -orbital is zero at the nucleus

Q33.The number of molecules or ions from the following, which do not have odd number of electrons are _____ . (A) NO2 (B) ICl−4 (C) BrF3 (D) ClO2 (E) NO+2 (F) NO

Q33.The number of atomic orbitals from the following having 5 radial nodes is 7s, 7p, 6s, 8p, 8d

Q33.Values of work function (W0) for a few metals are given below Metal Li Na K Mg Cu Ag W0 eV 2. 42 2. 3 2. 25 3. 7 4. 8 4. 3 The number of metals which will show photoelectric effect when light of wavelength 400 nm falls on it is _____ Given: h = 6. 6 × 10–34 J s c = 3 × 108 ms–1 e = 1. 6 × 10–19 C

Q33.Sum of π-bonds present in peroxodisulphuric acid and pyrosulphuric acid is

Q34.The number of species having a square planar shape from the following is XeF4, SF4, SiF4, BF4−, BrF4−, [Cu (NH3)4]2+, [FeCl4]2−, [PtCl4]2−