Identify the correct statements among the following.
(A) At 0 K, the resistance of a semiconductor is infinite.
(B) In an n-type semiconductor, the electron concentration is approximately equal to the concentration of donor atoms.
(C) In p-type semiconductors, the acceptor levels lie near the conduction band.
(D) In n-type semiconductors, the charge carriers are both electrons and holes.
Choose the correct answer from the options given below:

A symmetrical double convex lens is cut into two equal parts by a plane containing the principal axis. The power of the divided lens is :

The graphs of stopping potential versus frequency of incident radiation for two metals A and B are given.
Identify the correct statement(s) from the following:

(A) The slope of the graphs is equal to the Planck's constant.
(B) Intercept on the (-y) axis is equal to (work function/e).
(C) Threshold frequency for metal A is higher than metal B.
(D) Work function for metal B is greater than metal A.
Choose the correct answer from the options given below:

Hole is-

Two polaroid \( P_1 \) and \( P_3 \) are placed such that their pass-axis are mutually perpendicular. Another polaroid \( P_2 \) is rotated between \( P_1 \) and \( P_3 \). For what angle \( \theta \) between \( P_1 \) and \( P_2 \) the intensity of light emerging from \( P_3 \) will be maximum ?

A deutron and an \(\alpha\)-particle moving with the same velocity enter into a uniform magnetic field acting normal to the plane of their motion. The ratio of the circular paths described by the deutron and \(\alpha\)-particle is

When a capacitor is subjected to a D.C. source it takes small time internal to get fully charged up. During this small time interval there is no passage of charge through dielectric, yet we use a term - displacement current. This term is used because :

Match List-I with List-II

List-I	List-II
(A) The standard resistance coil	(I) Nickel-chromium alloy
(B) The connecting wire	(II) tin-lead alloy
(C) The heating wire	(III) copper metal
(D) The fuse wire	(IV) copper manganese nickel alloy

Choose the correct answer from the options given below:

The correct statement (s) for cubic close packed (ccp) three dimensional structure are :
(A) The number of the neighbours of an atom present in the top most layer is 12.
(B) The efficiency of atom packing is \(74\%\).
(C) The number of octahedral and tetrahedral voids per atom are 1 & 2, respectively.
(D) The unit cell edge length is \(2\sqrt{2}\) times the radius of the atom.
(E) The metals like Be, Cd, Mg, Zn have cubic close packed (ccp) structure.
Choose the correct answer from the options given below :

Arrange the following ions in increasing order of number of 3d-electrons
(A) Cr²⁺
(B) Cu⁺
(C) Ti³⁺
(D) Mn⁺
Choose the correct answer from the options given below :

In an inductive circuit, the current falls from 7.5 A to 1.5 A in 0.15 s. It induces emf of 220 V in the inductive coil. The inductance of the circuit is

Four lenses of focal length ±5 cm and ±200 cm are available for making a telescope. To produce the largest magnification for making a telescope with the help of these lenses, the focal length of eye piece should be :

Read the passage carefully and answer the questions
Ethers with the general formula \(C _n H _{2 n+2} O\) and functional group C-O-C may be divided as symmetrical and unsymmetrical.
Lower symmetrical ether may be obtained by the dehydration of alcohols at low temperatures in the presence of protic acids,
such as \(H _2 SO _4\) and \(H _3 PO _4\) whereas at high temperature intramolecular dehydration takes place.
Formation of ether from primary alcohols is also accompanied by the formation of small amount of alkenes.
Due to the steric hinderance, secondary and tertiary alcohols undergo elimination reaction rather than substitution reaction yielding alkene as major product. Ethers can also be obtained by heating alkyl halides with sodium or potassium alkoxides.
Substituted Ethers (secondary & tertiary) can also be prepared using this method.
If primary halides are replaced with secondary and tertiary halides, alkenes are the major products. The compound with the lowest boiling point is