List of practice Questions

Dependence of intensity of gravitational field (E) of earth with distance (r) from centre of earth is correctly represented by

If the focal length of objective lens is increased then magnifying power of:

The angle of a prism is 'A'. One of its refracting surfaces is silvered. Light rays falling at an angle of incidence 2A on the first surface returns back through the same path after suffering reflection at the silvered surface. The refractive indexµ, of the prism is

The given graph represents V – I characteristic for a semiconductor device

Which of the following statement is correct?

The number of possible natural oscillations of air column in a pipe closed at one end of length 85 cm whose frequencies lie below 1250Hz are: (velocity of sound = 340 ms^-1)

The oscillation of a body on a smooth horizontal surface is represented by the equation,
X = A cos (ωt)
where X = displacement at time t
        ω = frequency of oscillation
Which one of the following graphs shows correctly the variation 'a' with 't'?
Here a acceleration at time t
T = time period

Two cities are 150 km apart. Electric power is sent from one city to another city through copper wires. The fall of potential per km is 8 volt and the average resistance per km is 0.5Ω. The power loss in the wire is:

A thin semicircular conducting ring (PQR) of radius 'r' is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across the ring when its speed is v, is:

Following figures show the arrangement of bar magnets in different configurations. Each magnet has magnetic dipole moment \(\overrightarrow{m}\). Which configuration has highest net magnètic dipole moment?

In an ammeter 0.2% of main current passes through the galvanometer. If resistance of galvanometer is G, the resistance of ammeter will be:

Two identical long conducting wires AOB and COD are placed at right angle to each other, with one above other such that 'O' is their common point for the two. The wires carry I₁ and I₂ currents, respectively. Point 'P' is lying at distance 'd' from 'O' along a direction perpendicular to the plane containing the wires. The magnetic field at the point 'P' will be:

A conducting sphere of radius R is given a onducting charge Q. The electric potential and the electric field at the centre of the sphere respectively are:

A thermodynamic system undergoes cyclic process ABCDA as shown in Fig. The work done by the system in the cycle is:

Copper of fixed volume 'V' is drawn into wire of length 'l'. When this wire is subjected to a constant force 'F', the extension produced in the wire is 'Δl'. Which of the following graphs is a straight line?

If n₁, n₂ and n₃ are the fundamental frequencies of three segments into which a string is divided, then the original fundamental frequency n of the string is given by:

The resistances in the two arms of the meter bridge are 5Ω and RΩ, respectively. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6 l₁. The resistance 'R', is:

Two thin dielectric slabs of dielectric constants K₁ and K₂ (K₁ < K₂) are inserted between plates of a parallel plate capacitor, as shown in the figure. The variation of electric field 'E' between the plates with distance 'd' as measured from plate P is correctly shown by:

For the reaction:
\(X_2O4(l) → 2XO_2(g)\)
△U = 2.1 k cal, △S = 20 cal K^–l at 300 K.
Hence △G is

Identify \(Z\) in the sequence of reactions:
\(CH_3CH_2CH=CH_2  \xrightarrow{HBr/H_2O_2}Y \xrightarrow{C_2H_5ONa}Z\)

In the following reaction, the product (A) is :

Using the Gibbs energy change, \(△G° = + 63.3\  kJ\), for the following reaction,
\(Ag_2CO_3 (g) ⇋ 2Ag+ (aq) + CO_3^{2–} (aq)\)
the \(K_{sp}\) of \(Ag_2CO_3 \)(s) in water at \(25°C\) is :
\((R = 8.314\ J K^{–1} mol^{–1})\)

Which of the following will not be soluble in sodiumhydrogen carbonate?

A gardener is digging a plot of land. As he gets tired, he works more slowly. After $' t '$ minutes he is digging at a rate of $\frac {2} {\sqrt {t}} $square metres per minute. How long will it take him to dig an area of $40$ square metres ?

A steady current flows in a long wire. It is bent into a circular loop of one turn and the magnetic field at the centre of the coil is $ B $ . If the same wire is bent into a circular loop of $ n $ turns, the magnetic field at the centre of the coil is

Two concentric hollow spherical shells have radii $ r $ and $ R \left(R\,>>\,r\right) $ . A charge $ Q $ is distributed on them such that the surface charge densities are equal. The electric potential at the centre is