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A block of mass m is kept on a platform which starts from rest with constant acceleration g/2 upward, as shown in fig. Work done by normal reaction on block in time t is :

a. 3mg2t2/8 b. -mg2t2/8 c. mg2t2/8 d. 0 Answer: a S = ut+(1/2)at2 ut = 0 a = g/2 S = (1/4)gt2 N-mg = mg/2 N = 3mg/2 Work... View Article

A piece of wood of mass 0.03 kg is dropped from the top of a building 100 m high. At the same time, a bullet of mass 0.02 kg is fired vertically upward with a velocity of 100 m/s from the ground the bullet gets embedded in the wooded piece after striking. Then the maximum height to which the combined system reaches above the building before falling below is: (take g = 10ms^-2).

a. 40 b. 30 c. 20 d. 10 Answer: a Time taken by the particles to collide, t = d/Vrel = 100/100 = 1 sec Before collision, speed of... View Article

In the cube of side ‘a’ shown in the figure, the vector from the central point of the face ABOD to the central point of the face BEFO will be

a. b. c. d. Answer: c Position vector of G is Position vector of H is... View Article

Two guns A and B can fire bullets at speeds 1 km/s and 2 km/s respectively. From a point on a horizontal ground, they are fired in all possible directions. The ratio of maximum areas covered by the bullets fired by the two guns, on the ground is :

a. 1:2 b. 1:16 c. 1:8 d. 1:4 Answer: b R = u2sin 2θ/g For gun A, (Rmax)A = uA2/g For gun B, (Rmax)B = uB2/g (Area)A/(Area)B =... View Article

The density of a material in SI units is 128 kg m^-3. In certain units in which the unit of length is 25 cm and the unit of mass is 50 g, the numerical value of density of the material is :

a. 40 b. 410 c. 640 d. 16 Answer: a Density = mass/volume δ = M/V = M/L3 n1u1 = n2u2 n1 = 128 128[M1L1-3] = n2[M2L2-3] n2 =... View Article

On dissolving 0.5 g of non-volatile, non-ionic solute to 39 g of benzene, its vapour pressure decreases from 650 mm of Hg to 640 mm of Hg. The depression of freezing point of benzene (in K) upon addition of the solute is __________________. [Given data: Molar mass & molar freezing point depression of benzene is 78 g mol^-1 & 5.12 K Kg mol^-1]

Answer: (1.03 or 1.02) Therefore, M = 64 g... View Article

Consider the kinetic data given in the following table for the reaction A + B + C → Product

When [A] = 0.15 [B] = 0.25 [C] = 0.15 Rate of reaction is Y × 10-5 m/s. Find Y. Answer: (6.75) Let From (1), (2) -> y = 0 (1),... View Article

Which of the following compounds contain bond between same type of atoms.

N2O4, B3 N3H6, H2S2O3, N2O, H2S2O8, B2H6 Answer: N2O4, H2S2O3, N2O, H2S2O8... View Article

Schemes 1 and 2 describe the conversion of P to Q and R to S, respectively. Scheme 3 describes the synthesis of T from Q and S. The total number of Br atoms in a molecule of T is _____

Answer: (4) Total Br atoms = 4... View Article

For the following reaction, equilibrium constant K_c at 298 K is 1.6 × 10¹⁷.

When equal volume of 0.06 M Fe+2 and 0.2 M S-2 solution are mixed, then equilibrium concentration of Fe+2 is found to be Y × 10-17 M. Y is:... View Article

At 143 K, the reaction of XeF₄ with O₂F₂ produces a xenon compound Y. The total number of lone pair(s) of electron present on the whole molecule of Y is ____

Answer: (19) Distorted octahedral shape. Total no. of lone pair present on the whole molecule of Y = 1 ℓ. p. in Xe + 18. ℓ. p. in F = 19... View Article

Which of the following is/are correct regarding root mean square speed (U_rms) & average translation K.E. (E_av) of molecule in a gas at equilibrium.

a) Eav is doubled when its temperature is increased 4 times b) Urms is inversely proportional to the square root of its molecular mass c) Eav... View Article

Identify the option where all four molecules possess permanent dipole moment at room temperature.

a) BF, O3, SF6, XeF6 b) BeCl2, CO2, BCl3, CHCl3 c) SO2, C6H5Cl, H2Se, BrF5 d) NO2, NH3, POCl3, CH3Cl Answer: (c, d) For Option c... View Article

Which of the following are true.

a) Monosachharides can not be hydrolysed to give polyhydroxy aldehydes and ketones. b) Oxidation of glucose with bromine water gives glutamic... View Article

Choose the corection option for the following reaction

Answer: (1, 4)... View Article

Fusion of MnO₂ along with KOH and O2 forms X. Electrolytic oxidation of X yields Y. X undergoes disproportionation reaction in acidic medium to MnO2 and Y. The Manganese in X and Y is in the form W & Z respectively, then

a) W & Z are coloured b) W is diamagnetic and Z is paramagnetic c) Both W & Z are tetrahedral in shape d) Both W & Z involve pπ-dπ... View Article