A magnet of magnetic moment \( 50 \hat{i} \text{ A m}^2 \) is placed along the X-axis in a magnetic field \( \vec{B} = (0.5 \hat{i} + 3.0 \hat{j}) \text{ T} \). The torque acting on it is

The torque acting on a magnet of magnetic length 8 cm and pole strength 20 A m placed in a magnetic field of \( 3 \times 10^{-5} \, T \) at an angle of \( \pi/6 \) rad will be

The given graph shows the variation of terminal potential difference V, across the combination of three identical cells in series to an external resistor versus the current i in the circuit. The internal resistance of each cell is :

Which combination is to be selected for better tuning of an LCR series circuit used for communication ?

In a moving coil galvanometer, the coil is wound over a metallic frame in order to

A point source heating device of 1000 W with 10% efficiency is 7m from the observational location. Find the peak value of electric field produced by the radiation at that location.

Germanium and silicon behave as semiconductors because

A 50 cm long air core solenoid has a 2 cm radius and 500 turns. The self-inductance of the solenoid would be (given \(\mu_0=4 \pi \times 10^{-7} \operatorname{Tm} * A^{-1}\) and \(\pi^2=10\) )

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Aldehydes are generally more reactive than ketones in nucleophilic addition reactions due to steric and electronic reasons. Sterically, the presence of two relatively large substituents in ketones hinders the approach of nucleophile to carbonyl carbon more than aldehydes having only one such substituent Electronically aldehydes are more reactive than ketones because two alkyl groups reduce the elctrophilicity of the carbonyl more effectively than in former.
4-Hydroxy-4-methylpentan-2-one and 4-methylpent-3-en-2-one are the products obtained from A by aldol
condensation. \(A\) is:

The value of \(3^{18}(\bmod 4)\) is equal to

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Kinetic studies not only help us to determine the rate of a chemical reaction but also describe the conditions by which the reaction rates can be altered. The factors such as concentration, temperature, pressure and catalyst affect the rate of a reaction. The speed of a reaction or the rate of a reaction can be defined as the change in concentration of a reactant or product in unit time.
Rate \(= \text{k}[\text{A}]^x [\text{B}]^y\)
Here k is the rate constant
\(x + y\) gives the overall order of a reaction, whereas \(x\) and \(y\) represent the order with respect to the reactants A and B, respectively.
Which of the following statements are correct?
(A) Catalysts increase the rate of a chemical reaction.
(B) Catalysts can catalyze both spontaneous and non-spontaneous reactions.
(C) Higher the activation energy for a chemical reaction, lower is the rate of the reaction.
(D) Catalyst increases the potential energy barrier.
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As aldehydes ketones possess the carbonyl functional group, they show similar reactions. They exhibit nucleophilic addition reactions, reduction, oxidations, reactions due to alpha-Hydrogen atom, and many other reactions, like Cannizzaro reaction to electrophilic substitution reactions (in case of aromatic aldehydes ketones).
These reactions help in the preparation of a number of important compounds, like acetic acid, vinyl acetate, polymers and in perfume and dye industries. Nucleophilic addition reactions form cyanohydrins, acetals, alcohols and N -substituted derivatives like imine, oxime, semicarbazone, phenylhydrazone Schiff's base. Reactions due to alpha-hydrogen atoms help in formation of aldols and alpha, beta-unsaturated aldehydes ketones.
Which of the following does not give iodoform test?


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Four identical bulbs are connected in series with a source. These together dissipate a power P. The power dissipated, if the four bulbs are connected in parallel with the same source, will be