X and Y are two volatile liquids with molar weights of 10 g mol^(-1) and 40 g mol^(-1) respectively. Two cotton plugs, one soaked in X and the other soaked in Y, are simultaneously placed at the ends of a tube of length L = 24 cm, as shown in the fig... Read more X and Y are two volatile liquids with molar weights of 10 g mol^(-1) and 40 g mol^(-1) respectively. Two cotton plugs, one soaked in X and the other soaked in Y, are simultaneously placed at the ends of a tube of length L = 24 cm, as shown in the figure. The tube is filled with an inert gas at 1 atmosphere pressure and a temperature of 300 K. Vapours of X and Y react to form a product which is first observed at a distance d cm from the plug soaked in X. Take X and Y to have equal molecular diameters and assume ideal behaviour for the inert gas and the two vapours. The value of d in cm (shown in the figure), as estimated from Graham’s law, is.
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12
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16
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20

The acidic hydrolysis of ether (X) shown below is fastest when The acidic hydrolysis of ether (X) shown below is fastest when
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one phenyl group is replaced by a methyl group.
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one phenyl group is replaced by a para-methoxyphenyl group.
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two phenyl groups are replaced by two para-methoxyphenyl groups.
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no structural change is made to X.

During an experiment with a metre bridge, the galvanometer shows a null point when the jockey is pressed at 40.0 cm using a standard resistance of 90 ohm, as shown in the figure. The least count of the scale used in the metre bridge is 1 mm . The unk... Read more During an experiment with a metre bridge, the galvanometer shows a null point when the jockey is pressed at 40.0 cm using a standard resistance of 90 ohm, as shown in the figure. The least count of the scale used in the metre bridge is 1 mm . The unknown resistance is
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60 ± 0.15Ω
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135 ± 0.56Ω
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60 ± 0.25Ω
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135 ± 0.23Ω

A wire, which passes through the hole in a small bead, is bent in the form of quarter of a circle. The wire is fixed vertically on ground as shown in the figure. The bead is released from near the top of the wire and it slides along the wire without ... Read more A wire, which passes through the hole in a small bead, is bent in the form of quarter of a circle. The wire is fixed vertically on ground as shown in the figure. The bead is released from near the top of the wire and it slides along the wire without friction. As the bead moves from A to B, the force it applies on the wire is
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always radially outwards
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always radially inwards
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radially outwards initially and radially inwards later
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radially inwards initially and radially outwards later

A tennis ball is dropped on a horizontal smooth surface. It bounces back to its original position after hitting the surface. The force on the ball during the collision is proportional to the length of compression of the ball. Which one of the followi... Read more A tennis ball is dropped on a horizontal smooth surface. It bounces back to its original position after hitting the surface. The force on the ball during the collision is proportional to the length of compression of the ball. Which one of the following sketches describes the variation of its kinetic energy with time most appropriately? The figures are only illustrative and not to the scale.
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A
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B
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D