The core of electromagnets are made of ferromagnetic material like soft iron because the soft iron has-

The work function of a photosensitive material is 4.0 eV. The longest wavelength of light that can cause electron emission from the material is (approximately)

Which of the following statements are true?
(A) Rheostat can be used both as a variable resistance and a potential divider.
(B) An electrical circuit is functional only if all the components of the circuit are connected in proper order, assuming that all circuit components/ devices are in working condition and key is closed.
(C) An open circuit means a break in some part of a circuit which could be deliberate such as a key in open position or a fault such as broken wire or burnt out component(s) or loose connection.
(D) Rheostat as a potential divider gives variable resistance.
Choose the correct answer from the options given below:

Identify the correct statements.
(A) Electric charge is quantized.
(B) Electric charge on any object is always an integral multiple of e.
(C) The coulomb force is weaker than the gravitational force.
(D) The coulomb force is a conservative force.
Choose the correct answer from the options given below:

An electron moving with velocity of \(5.4 \times 10^6\) m/sec. What is the de-Broglie wavelength associated with them (\(h = 6.63 \times 10^{-34}\) J/s)

When the electron in a hydrogen atom jumps from the 2nd orbit to the 1st orbit, the wavelength of the radiation emitted is \(\lambda\).
When the electron jumps from the 3rd orbit to the 1st orbit, the wavelength of emitted radiation is:

Choose the incorrect statements from the following:
(A) The energy density of an electric field in electromagnetic waves is \( (\epsilon_0 E^2/2) \).
(B) The total energy of electromagnetic waves falling on a surface is \( E = 6.0 \times 10^5 \text{ J} \) and the momentum delivered to the surface, if absorbed fully, is \( p = 2 \times 10^3 \text{ kg m/s} \).
(C) The speed of the electromagnetic waves is \( E_0 / B_0 \).
(D) The energy density of magnetic field in electromagnetic Waves is \( (B^2 / \mu) \).
Choose the correct answer from the options given below:

The vapour pressure of pure water at \(25^{\circ} C\) is 23.75 mmHg.
The vapour pressure of the solution obtained by dissolving 34.2 g of sucrose \(\left( C _{12} H _{22} O _{11}\right)\) in 100 g of water will be :

Which one of the following statements is incorrect about ecological pyramids?

Expand KVIC

If \(A X=B\) where \(A , X\) and B are matrices and \(A^{-1}, B^{-1}\) exist, then matrix X is

Read the passage carefully and answer the questions based on the passage:
Pollen pistil interaction involves all events from the landing of pollen grains on the stigma until the pollen tube enters the embryo sac (when the pollen is compatible). When a pollen tube grows through the style and enters into the ovules, it finally discharges two male gametes in one of the synergids. Syngamy and triple fusion are two fusion events occur in angiosperms. Thus, angiosperms exhibit double fertilization. The products of these fusions are the diploid zygote and triploid primary endosperm nucleus. Zygote develops into embryo and primary endosperm cell forms the endosperm tissue. The developing embryo passes through different stages before maturation.
Formation of diploid zygote is a result of:

Read the passage carefully and answer:
Organic compounds derived from NH3 by replacing one or more H-atoms with alkyl or aryl groups will form primary, secondary and tertiary amines. The common methods which include their preparations are reduction of nitro group, amide group and nitrile group, Gabriel phthalimide synthesis and ammonolysis of alkyl halides. Amines are basic in nature due to the presence of a lone pair of electrons on the nitrogen atom. Important chemical properties of amines include acylation, alkylation and their interaction with nitrous acid. There are various tests which can distinguish different types of amines from each other, for e.g. carbylamine test, Hinsberg's test, coupling reaction etc. Another important class of compounds which can be derived from primary amines is azo compounds. These compounds are intensely colored and widely used as dyes in textile, leather and food industries.
Conversion of nitro group into primary amine is preferred using