Class 12th

At 298 K, the standard electrode potentials of Cu²⁺/Cu, Zn²⁺ /Zn, Fe²⁺ /Fe and Ag⁺ /Ag are 0.34 V, -0.76 V, -0.44 V and 0.80 V, respectively. On the basis of standard electrode potential, predict which of the following reaction can not occur?

Which statement regarding polymers is not correct?

Given below are two statements : One is labelled as

Assertion (A) and the other is labelled as Reason (R).

Assertion (A): The stretching of a spring is determined by the shear modulus of the material of the spring.

Reason (R): A coil spring of copper has more tensile strength than a steel spring of same dimensions.

In the light of the above statements, choose the most appropriate answer from the options given below:

In a potentiometer circuit a cell of EMF $1.5\mathrm{V}$ gives balance point at $36\mathrm{c}\mathrm{m}$  length of wire. If another cel) of EMF 2.5 V replaces the first cell, then at what length of the wire, the balance point occurs?

The given graph is a representation of kinetics of a reaction.

The y and x axes respectively are for zero and first order reactions, respectively are:

A ball is projected with a velocity, $10{\mathrm{m}\mathrm{s}}^{-1}$ , at an angle of ${60}^{?}$  with the vertical direction, its speed at the highest pint of its trajectory will be :

Given below are half cell reactions:
MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O, E°(Mn²⁺/MnO₄⁻) = -1.510 V
½O₂ + 2H⁺ + 2e⁻ → H₂O, E°(O₂/H₂O) = +1.223 V

Will the permanganate ion, MnO₄⁻liberate O₂ from water in the presence of an acid?

A capacitor of capacitance ' $C$ ' is connected across an ac source of voltage $\mathrm{V}$ , given by $\mathrm{V}={\mathrm{V}}_0\mathrm{s}\mathrm{i}\mathrm{n}?\omega \mathrm{t}$ The displacement current between the plates of the capacitor, would then be given by:

The incorrect statement regarding enzymes is:

A convex lens ' $A$ ' of focal length $20\mathrm{c}\mathrm{m}$ and a concave lens ' $\mathrm{B}$ ' of focal length $5\mathrm{c}\mathrm{m}$ are kept along the same axis with a distance ' $d$ ' between them. If a parallel beam of light falling on ' $A$ ' leaves ' $B$ ' as a parallel beam, then the distance ' $\mathrm{d}$ ' in $\mathrm{c}\mathrm{m}$  will be: