The figure shows an experimental plot for discharging of a capacitor in an R-C circuit. The time constant $$\tau$$ of this circuit lies between

A cylindrical tube, open at both ends, has a fundamental frequency, $$f,$$ in air. The tube is dipped vertically in water so that half of it is in water. The fundamental frequency of the air-column is now :

Proton, deuteron and alpha particle of same kinetic energy are moving in circular trajectories in a constant magnetic field. The radii of proton, denuteron and alpha particle are respectively $$r_p,r_d$$ and $$r_{\alpha }$$. Which one of the following relation is correct?

A charge $$Q$$ is uniformly distributed over the surface of non-conducting disc of radius $$R.$$ The disc rotates about an axis perpendicular to its plane and passing through its center with an angular velocity $$\omega .$$ As a result of this rotation a magnetic field of induction $$B$$ is obtained at the center of the disc. If we keep both the amount of charge placed on the disc and its angular velocity to be constant and very the radius of the disc then the variation of the magnetic induction at the center of the disc will be represented by the figure :

A particle of mass $$m$$ is at rest at the origin at time $$t=0.$$ It is subjected to a force $$F\left(t\right)=F_0{e}^{-bt}$$ in the $$x$$ direction. Its speed $$v(t)$$ is depicted by which of the following curves?

A coil is suspended in a uniform magnetic field, with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating; It is very difficult to stop. But if an aluminium plate is placed near to the coil, it stops. This is due to :

The compressibility factor for a real gas at high pressure is :

Which branched chain isomer of the hydrocarbon with molecular mass 72u gives only one isomer of mono substituted alkyl halide ?

2–Hexyne gives trans–2–Hexene on treatment with :

Which among the following will be named as dibromidobis (ethylene diamine) chromium(III) bromide?

The pH of a 0.1 molar solution of the acid HQ is 3. The value of the ionization constant, Ka of this acid is :

The electrons identified by quantum numbers n and l : (a) n = 4, $$l$$ = 1 (b) n = 4, $$l$$ = 0 (c) n = 3, $$l$$ = 2 (d) n = 3, $$l$$ = 1 Can be placed in order of increasing energy as :

The increasing order of the ionic radii of the given isoelectronic species is :

Very pure hydrogen (99.9%) can be made by which of the following processes?

Lithium forms body centred cubic structure. The length of the side of its unit cell is 351 pm. Atomic radius of the lithium will be :

How many chiral compounds are possible on monochlorination of 2–methyl butane ?

What is DDT among the following?

Iodoform can be prepared from all except :

For a first order reaction, (A) $$\to$$ products, the concentration of A changes from 0.1 M to 0.025 M in 40 minutes. The rate of reaction when the concentration of A is 0.01 M is :

According to Freundlich adsorption isotherm, which of the following is correct ?