The correct order of acid strength of the following carboxylic acids is
Answer: (1)
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Which of the following set represent correct formula for Malachite, Magnetite, Calamine & Cryolite?
a) CuCO3, Fe2O3, ZnO, Al2O3 b) CuCO3,Cu(OH), Fe3O4, ZnCO3, Na3 AlF6 c) CuCO3, Fe3O4, ZnCO3, Al2O3 d) CuCO3.Cu(OH), Fe2O3, ZnCO3,... View Article
The balancing length for a cell is 560 cm in a potentiometer experiment. When an external resistance of 10 Ω is connected in parallel to the cell, the balancing length changes by 60 cm. If the internal resistance of the cell is N/10 Ω, the value of N is
Answer.(12) Let the emf of cell is Ɛ internal resistance is r and potential gradient is x. Ɛ = 560... View Article
The sum of two forces [latex]\vec{P}[/latex] and [latex]\vec{Q}[/latex] is [latex]\vec{R}[/latex] such that [latex]\vec{R}[/latex] = |P|[latex]\left | \vec{R} \right | = \left | \vec{P} \right |[/latex]. The angle θ (in degrees) that the resultant of [latex]\vec{2P}[/latex] and [latex]\vec{Q}[/latex] will make with [latex]\vec{Q}[/latex] is __
Answer: (90°)
Consider a uniform cubical box of side a on a rough floor that is to be moved by applying minimum possible force F at a point above its centre of mass (see figure). If the coefficient of friction is μ = 0.4, the maximum value of 100 ×b/a for the box not to topple before moving is __.
Answer: (50) F balances kinetic friction so that the block can move So, F = μmg For no toppling, the... View Article
M grams of steam at 1000C is mixed with 200g of ice at its melting point in a thermally insulated container. If it produces liquid water at 400 C[heat of vaporization of water is 540 cal/g and heat of fusion of ice is 80 cal/g ], the value of M is __.
Answer:(40) Here, heat absorbed by ice = mice Lf + mice Cw(40-0) Heat released by steam = msteam Lv +... View Article
A 60 pF capacitor is fully charged by a 20 V supply. It is then disconnected from the supply and is connected to another uncharged 60 pF capacitor in parallel. The electrostatic energy that is lost in this process by the time the charge is redistributed between them is __(in nJ)
Answer: (6) V0 = 20 V Initial potential energy Ui = ½ CV02 After connecting identical capacitor in parallel, voltage... View Article
The dimension of B2/2μ0 where B is magnetic field and μ0 is the magnetic permeability of vacuum, is
a. ML-1T-2 b. ML2T-2 c. MLT-2 d. ML2T-1 Answer: (a) Energy density in magnetic field = B2/2 μ0 = force... View Article
An emf of 20 V is applied at time t = 0 to a circuit containing in series 10 mH inductor and 5 Ω resistor. The ratio of the currents at time t = ∞ and t = 40 s is close to take e2= 7.389)
a. 1.06 b. 1.46 c. 1.15 d. 0.84 Answer: (a) i = i0( 1- e-t/L/R) = (20/5)( 1-e-t/0.01/5) = 4(1-e-500t)... View Article
The figure gives experimentally measured B vs H variation in a ferromagnetic material. The retentivity, coercivity and saturation, respectively, of the material are
a. 1.5 T, 50 A/m, 1 T b. 1 T, 50 A/m, 1.5 T c. 1.5 T, 50 A/m, 1... View Article
An elevator in a building can carry a maximum of 10 persons, with the average mass of each person being 68 kg. The mass of the elevator itself is 920 kg and it moves with a constant speed of 3 m/s. The frictional force opposing the motion is 6000N. If the elevator is moving up with its full capacity, the power delivered by the motor to the elevator (g = 10 m/s2) must be atleast
a. 66000 W b. 63360 W c. 48000 W d. 56300 W Answer: (a) Net force on motor will be... View Article
A thin lens made of glass (refractive index 1.5) of focal length f = 16 cm is immersed in a liquid of refractive index 1.42. If its focal length in liquid is fi, then the ratio fl/ f is closest to the integer
a. 9 b. 17 c. 1 d. 5 Answer: (a) \(\begin{array}{l}\frac{1}{f_{a}} = \left ( \frac{\mu _{g}}{\mu _{a}} -1\right )\left (... View Article
A planar loop of wire rotates in a uniform magnetic field. Initially at t = 0, the plane of the loop is perpendicular to the magnetic field. If it rotates with a period of 10 s about an axis in its plane, then the magnitude of induced emf will be maximum and minimum, respectively at
a. 2.5 sec and 5 sec b. 5 sec and 7.5 sec c. 2.5 sec and 7.5 sec d. 5... View Article
An electron (of mass m) and a photon have the same energy E in the range of few eV. The ratio of the de Broglie wavelength associated with the electron and the wavelength of the photon is. ( c = speed of light in vacuum)
a. (E/2m)1/2 b. 1/c (2E/m)1/2 c. c(2mE)1/2 d. 1/c (E/2m)1/2 Answer: (d) λd for electron = h/√(2me) λp for photon... View Article
A stationary observer receives sound from two identical tuning forks, one of which approaches and the other one receded with the same speed (much less than the speed of sound). The observer hears 2 beats/sec. The oscillation frequency of each tuning fork is v0 = 1400 Hz and the velocity of sound in air is 350 m/s. The speed of each tuning fork is close to
a. 1/4 m/s b. 1 m/s c. 1/2 m/s d. 1/8 m/s Answer: (a) f0 C/(C-V)- f0C/(C+V)= 2 V =... View Article
A particle of mass m and charge q has an initial velocity [latex]vec{v} = v_{0}: hat{j}[/latex]. If an electric field [latex]vec{E} = E_{0}: hat{i}[/latex] and magnetic field [latex]vec{B} = B_{0}: hat{i}[/latex] act on the particle, its speed will double after a time
a. √3mv0/qE0 b. √2mv0/qE0 c. 3mv0/qE0 d. 2mv0/qE0 Answer: (a) Magnetic field can only change direction of speed as it... View Article
In the figure, potential difference between a and b is
a. 0 V b. 15 V c. 10 V d. 5 V Answer: (c) Diode is in forward bias, so... View Article
An ideal fluid flows (laminar flow) through a pipe of non-uniform diameter. The maximum and minimum diameters of the pipes are 6.4 cm and 4.8 cm, respectively. The ratio of minimum and maximum velocities of fluid in this pipe is
a. √(3/2) b. 9/16 c. 3/4 d. √3/4 Answer: (b) Given, Maximum diameter of pipe = 6.4 Minimum diameter of... View Article
The activity of a radioactive substance falls from 700 s-1 to 500 s-1 in 30 minutes. Its half life is close to
a. 66 min b. 62 min c. 52 min d. 72 min Answer: (b) Using the half-life equation ln A0/At... View Article
Two ideal Carnot engines operate in cascade (all heat given up by one engine is used by the other engine to produce work) between temperatures T1 and T2. The temperature of the hot reservoir of the first engine is T1 and the temperature of the cold reservoir of the second engine is T2. T is the temperature of the sink of first engine which is also the source for the second engine. How is T related to T1 and T2 if both the engines perform equal amount of work?
a. T = 2T1T2/(T1+T2) b. T = (T1+T2)/2 c. T = 0 d. T = √T1T2 Answer: (b) Heat input... View Article
