When a potential difference is applied across a copper wire, the drift velocity of the electrons is v. If the same potential difference is applied across another copper wire of the same length but twice the diameter, the drift velocity of electrons will be

Resistivity of a conductor depends on

A charge q is enclosed by a spherical Gaussian surface of radius R. If the radius of the sphere is doubled, how will the outward electric flux change?

The magnetic field in a plane electromagnetic wave is given by \( B_y = 2 \times 10^{-7} \sin(0.5 \times 10^3 x + 1.57 \times 10^{11} t) \text{ T} \). The frequency of the wave is

The electric field intensity at the mid point of a dipole with charge \( \pm q \) and dipole length \( 2a \) is:

A battery of emf 3 V and internal resistance r is connected in series with a resistor of \( 55 \text{ } \Omega \). An ammeter of resistance \( 2 \text{ } \Omega \) connected in circuit reads 50 mA. The value of r is

A vertical electric field of magnitude \( 4.9 \times 10^5 \text{ NC}^{-1} \) just prevents a water droplet of mass \( 0.1 \text{ g} \) from falling. What is the charge on the droplet? Take acceleration due to gravity \( 9.8 \text{ ms}^{-2} \).

The karyotype of a person with Turner's syndrome is:

Observe the given figures and answer the question

Biogenesis is:

What physical quantity is the same for X-rays of wavelength \( 10^{-10} \) m, red light of wavelength 680 nm and radiowaves of wavelength 50 m?

If A is a skew-symmetric matrix, then which of the following statements is NOT true?
(A) A is singular if order of A is odd
(B) A is non-singular
(C) \(A^{2025}\) is a skew-symmetric matrix
(D) \(A^{2025}\) is a symmetric matrix
(E) all diagonal elements of A are zeros
Choose the correct answer from the option given below :

Read the passage given below and answer the question.
The transition elements which give the greatest number of oxidation states occur in or near the middle of the series. Manganese, for example, exhibits all the oxidation states from +2 to +7 . The lesser number of oxidation states at extreme ends stems from either too few electrons to lose or share (Sc, Ti) on too many d-electrons (hence fewer orbitals available in which to share electrons with others) for higher valence \(( Cu , Zn )\). Thus early in the series scandium (II) is virtually unknown and titanium (IV) is more stable than Ti (III) or Ti (II). At the other end, the only oxidation state of zinc is \(+ 2\) (no d electrons are involved). The maximum oxidation states of reasonable stability correspond in value to the sum of the s - and d-electrons upto manganese ( \(Ti ^{I V} O _2, V^V O _2^{+}, Cr ^{V I} O _4^{2-}\), \(Mn ^{\text {VII }} O _4\) ) followed by a rather abrupt decrease in stability of higher oxidation states, so that the typical species to follow are \(Fe ^{I I, I I I}, Co ^{I I, I I I}, Ni ^{I I}, Cu ^{I, I I}, Zn ^{I I}\).
The variability of oxidation states, a characteristic of transition elements, arises out of incomplete filling of d-orbitals in such a way that their oxidation states differ from each other by unity, e.g. \(V ^{I I}, V^{I I I}, V^{I V}, V^V\). This is in contrast with the variability of oxidation states of non transition elements where oxidation states normally differ by a unit of two.
An interesting feature in the variability of oxidation states of the d-block elements is noticed among the groups (groups 4 through 10). Although in the p-block, the lower oxidation states are favoured by the heavier members (due to inert pair effect), the opposite is true in the groups of dblock. For example, in group 6, \(Mo ( VI )\) and \(W ( VI )\) are found to be more stable than \(Cr ( VI )\). The \(Cr ( VI )\) in the form of dichromate in acidic medium is a strong oxidising agent, whereas \(MoO _3\) and \(WO _3\) are not.
Low oxidation states are found when a complex compound has ligands capable of \(\pi\)-acceptor character in addition to the \(\sigma\)-bonding. For example, in \(Ni ( CO )_4\) and \(Fe ( CO )_5\), the oxidation state of nickel and iron is zero.
Most acidic species among the following is :

The correct 4f sub-shell electronic configuration of Yb²⁺ion is