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Statement I: Alkali metals dissolve in liquid ammonia to give blue solutions.
Statement II: Alkali metals in liquid ammonia give solvated species of the type \({\left[{M}{\left({N}{H}_{{{3}}}\right)}_{{{n}}}\right]}^{{\oplus}}\) (M = alkali metals).
(A) Statement I is correct , Statement II is correct , Statement II is the correct explanation of Statement I
(B) Statement I is correct , Statement II is correct , Statement II is not the correct explanation of Statement I
(C) Statement I is correct , Statement II is incorrect
(D) Statement I is incorrect , Statement II is correct

Answer

Answer: B
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Conisder the chemical reaction
\({N}_{{{2}}}{\left({g}\right)}+{3}{H}_{{{2}}}{\left({g}\right)}\rightarrow{2}{N}{H}_{{{3}}}{\left({g}\right)}\)
The rate of this reaction can be expressed in terms of time derivatives of the concentration of \({N}_{{{2}}}{\left({g}\right)},{H}_{{{2}}}{\left({g}\right)}\), or \({N}{H}_{{{3}}}{\left({g}\right)}\). Identify the correct relationship among the rate expresisons.
(A) \({R}{a}{t}{e}=-\frac{{{d}{\left[{N}_{{{2}}}\right]}}}{{\left.{d}{t}\right.}}=-\frac{{1}}{{3}}\frac{{{d}{\left[{H}_{{{2}}}\right]}}}{{\left.{d}{t}\right.}}=\frac{{1}}{{2}}\frac{{{d}{\left[{N}{H}_{{{3}}}\right]}}}{{\left.{d}{t}\right.}}\)
(B) \({R}{a}{t}{e}=-\frac{{{d}{\left[{N}_{{{2}}}\right]}}}{{\left.{d}{t}\right.}}=-{3}\frac{{{d}{\left[{H}_{{{2}}}\right]}}}{{\left.{d}{t}\right.}}={2}\frac{{{d}{\left[{N}{H}_{{{3}}}\right]}}}{{\left.{d}{t}\right.}}\)
(C) \({R}{a}{t}{e}=-\frac{{{d}{\left[{N}_{{{2}}}\right]}}}{{\left.{d}{t}\right.}}=\frac{{1}}{{3}}\frac{{{d}{\left[{H}_{{{2}}}\right]}}}{{\left.{d}{t}\right.}}=\frac{{1}}{{2}}\frac{{{d}{\left[{N}{H}_{{{3}}}\right]}}}{{\left.{d}{t}\right.}}\)
(D) \({R}{a}{t}{e}=-\frac{{{d}{\left[{N}_{{{2}}}\right]}}}{{\left.{d}{t}\right.}}=-\frac{{{d}{\left[{H}_{{{2}}}\right]}}}{{\left.{d}{t}\right.}}=\frac{{{d}{\left[{N}{H}_{{{3}}}\right]}}}{{\left.{d}{t}\right.}}\)
A body dropped from a height h with an initial speed zero, strikes the ground with a velocity \({3}{k}\frac{{m}}{{h}}\). Another body of same mass is dropped from the same height h with an initial speed \(-{u}'={4}{k}{m}/{h}\). Find the final velocity of second body with which it strikes the ground
(A) \({3}{k}{m}/{h}\)
(B) \({4}{k}\frac{{m}}{{h}}\)
(C) \({5}{k}{m}/{h}\)
(D) \({12}{k}{m}/{h}\)
A stone is shot straight upward with a speed of \(20  \ m/sec\) from a  tower \(200  \ m\) high. The speed with which it strikes the ground is approximately  ( )
A. \({60} \ {m}/{\sec{}}\)
B. \({65} \ {m}/{\sec{}}\)
C. \({70} \ {m}/{\sec{}}\)
D. \({75} \ {m}/{\sec{}}\)
Assertion: The average velocity of the object over an interval of time is either smaller than or equal to the average speed of the object over the same interval.
 Reason: Velocity is a vector quantity and speed is a scalar quantity.  ( )
A. If both assertion and reason are true and the reason is the correct explanation of the assertion.  
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.  
C. If assertion is true but reason is false.  
D. If the assertion and reason both are false
A block is kept on an inclined plane of inclination \(\theta\) of length l. the velocity of particle at the bottom of inclined is (the coefficient of friciton is \(\mu\))
(A) \(\sqrt{{{2}{g}{l}{\left(\mu{\cos{\theta}}-{\sin{\theta}}\right)}}}\)
(B) \(\sqrt{{{2}{g}{l}{\left({\sin{\theta}}-\mu{\cos{\theta}}\right)}}}\)
(C) \(\sqrt{{{2}{g}{l}{\left({\sin{\theta}}+\mu{\cos{\theta}}\right)}}}\)
(D) \(\sqrt{{{2}{g}{l}{\left({\cos{\theta}}+\mu{\sin{\theta}}\right)}}}\)
Assertion : Angle of repose is equal to angle of limiting friction.
Reason : When the body is just at the point of motion, the force of friction in this stage is called as limiting friction.

(A) If both assertion and reason are true and t he reason is the correct explanation of the assertion.
(B) If both assertion and reason are true but reason is not the correct explanation of the assertion.
(C) If assertion is true but reason is false
(D) If the assertion and reason both are false
5 g of ice at \({0}^{{\circ}}{C}\) is dropped in a beaker containing 20 g of water at \({40}^{{\circ}}{C}\) . The final temperature will be
(A) \({32}^{{\circ}}{C}\)
(B) \({16}^{{\circ}}{C}\)
(C) \({8}^{{\circ}}{C}\)
(D) \({24}^{{\circ}}{C}\)
A body of mass 2 kg is hung on a spring balance mounted vertically in a lift. If the lift descends with an acceleration equal to the acceleration due to gravity ‘ g ’, the reading on the spring balance will be
(A) 2 kg
(B) \({\left({4}\times{g}\right)}{k}{g}\)
(C) \({\left({2}\times{g}\right)}{k}{g}\)
(D) Zero
Assertion : The work done in bringing a body down from the top to the base along a frictionless inclined plane is the same as the work done in bringing it down along the vertical side .
Reason : The gravitational force on the body along the inclined plane is the same as that along the vertical side.
(A) If both assertion and reason are true and the reason is the correct explanation of the assertion
(B) If both assertion and reason are true but reason is not the correct explanation of the assertion
(C) If assertion is true but reason is false.
(D) If the assertion and reason both are false.
Two bodies moving towards each other collide and move away in opposite directions. There is some rise in temperature of bodies because a part of the kinetic energy is converted into
(A) Heat energy
(B) Electrical energy
(C) Nuclear energy
(D) Mechanical energy

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