A battery of emf 4 V and internal resistance \(1 \, \Omega\) is connected across a wire of resistance \(9.0 \, \Omega\). The number of electrons passing through the cross-section of the wire in 4 s is:

A straight long wire carrying a current of 30 A is placed in an external uniform magnetic field of \( 4 \times 10^{-4} \, T \) parallel to the current. The magnitude of the resultant magnetic field at a point 2 cm away from the wire is

From the given statements:
A. All photons in white light have same energy and momentum
B. When intensity of light increases the number of photons incident per second per unit area increases.
C. Photons are deflected by negative terminal of battery
D. Photoelectric (saturation) current increases with increase in the frequency of radiation
Choose the correct answer from the options given below:

The phenomenon of polarisation of light confirmed that light waves are

A planoconvex lens has the radius of curvature of its curved surface 50 cm and the refractive index of its material is 1.5. Its focal length will be

A difference of 2.21 eV separates two energy levels in an atom. What is the frequency of radiation emitted when the atom makes a transition from the upper level to the lower level?

An electric dipole of moment P is placed along the direction of electric field E. The work done in deflecting the dipole through 180° is equal to

A cell of emf 1.1 V and internal resistance 0.5 \(\Omega\) is connected to a 0.5 \(\Omega\) wire. Another cell of same emf is added in series, but current remains unchanged. The second cell's internal resistance is :

Cuckoo layings it's egg in the nest of crow for incubation is an example of-

Let \(f:[-2,2] \rightarrow[-2,2]\) be a function defined by \(f(x)=x|x|\), then \(f\) is:

The number of all possible matrices of order \(2 \times 3\) with each entry 0 or 1 is:

Which of the following complexes will show absorbance of light at the lowest wavelength?

Read the passage carefully and answer the questions
Sodium dichromate \(Na _2 Cr _2 O _7\) and Potassium dichromate \(K _2 Cr _2 O _7\) are strong oxidizing agents; in acidic solution, its oxidising action can be represented as follows :
\(Cr _2 O _7^{2-}+14 H ^{+}+6 e^{-} \rightarrow 2 Cr ^{3+}+7 H _2 O \left( E ^{\circ}=1.33 V\right)\)
The chromates and dichromates are interconvertible in aqueous solution depending upon pH of the solution.
The chromate ion is tetrahedral whereas the dichromate ion consists of two tetrahedra sharing one corner with \(Cr - O - Cr\) bond angle of \(126^{\circ}\)
Potassium permanganate is prepared by fusion of \(MnO _2\) with an alkali metal hydroxide and an oxidising agent like \(KNO _3\).
This produces the dark green \(K _2 MnO _4\) which disproportionates in a neutral or acidic solution to give permanganate. It is a strong oxidizing agent. Hydrogen ion concentration of the solution plays
an important part in the reduction of permanganate to manganate, manganese dioxide and manganese(II) salt.
Potassium permanganate forms dark purple (almost black) crystals which are isostructural with those of \(KClO _4\).
The salt is not very soluble in water \((6.4 g / 100 g\) of water at 293 K ), but when heated it decomposes at 513 K.
Potassium dichromate is used in the leather industry because of its nature as