Explore topic-wise InterviewSolutions in Current Affairs.

Configuration of two elements are: Al (z = 13) = [Ne]¹⁰ 3s² 3p¹; Si (z = 14) [Ne]¹⁰ 3s² 3p².

The unpaired electrons in silicon (Si) will experience more effective nuclear charge because the atomic number of the element Si is more than that of Al.

A solid substance may contain two types of impurities :

• Impurities which are soluble in the same solvent as the main substance.
• Impurities which are not soluble in the same solvent as the main substance.

Correct option is  D) all

Electromagnetic waves are produced when an electric charge vibrates.

There are seven colours in a rainbow. They are Violet, Indigo, Blue, Green, Yellow,Orange and Red

Correct option is D) Visible

∆ E= 2.18x 10^-18(1/n¹ ₂ – 1/n² ₂ )

= 2.18x 10^-18(1/5² – 1/2² )

 = -4.58 x 10^-19 J

 Frequency= ∆ E/h 

= 4.58 x 10^-19 J/6.626 x 10^-34 Hz 

=6.91 x 10¹⁴ Hz 

Wave length= C/V₀ 

=3x10⁸ /6.91x10¹⁴ 

=434 nm

A rainbow is a natural spectrum appearing in the sky.

According to Heisenberg uncertainty principle,

= \(\Delta \mathrm{x}\times\Delta p\) = \(\frac{h}{4\pi}\)

Given, \(\Delta\mathrm{x}=\Delta p\)

\(\therefore\) \((\Delta p)^2\) = \(\frac{h}{4\pi}\)

∆p = \(\sqrt{\frac{h}{4\pi}}\)

or m x ∆v = \(\sqrt{\frac{h}{4\pi}}\)

or ∆v = \(\frac{1}{m}\sqrt{\frac{h}{4\pi}}\) = \(\frac{1}{9.1\times10^{-31}}\sqrt{\frac{6.626\times10^{-34}}{4\times3.14}}\)

= \(\frac{0.726\times10^{-17}}{9.1\times10^{-31}}\)

= 7.98 × 10¹² ms⁻¹

Hence, uncertainty in velocity is greater than the velocity of light which is impossible. Thus, the two uncertainties cannot be equal in magnitude.

 1. Atom is neutral. 

2. Whole mass is concentrated in nucleus.

3. Electrons are revolving in orbits.

It could not explain the stability of an atom. 

= It could not explain the line spectrum of H- atom. 

(i) Cathode rays (beam of electrons) when focused on a heavy metal like tungsten, molybdenum etc. produce X-rays which find wide applications in medical field. Also, electron microscope which uses a beam of electrons to illuminate a specimen (an extremely small piece) produces a magnified image. 

(ii) Proton therapy is a type of particle therapy which uses a beam of protons to irradiate disease tissue, most often in the treatment of cancer. 

(iii) NMR spectroscopy is used to determine the structure of an organic compound by revealing the hydrogen and carbon skeleton. 

(iv) When a neutron hits uranium, a chain reaction is set up accompanied with evolution of tremendous amount of energy. The energy can be used in the atom bomb for destruction or it can be used in the nuclear reactor to produce electricity.

Hund’s rule: The orbitals of equal energy (degenerate) are occupied with one electron each before the pairing of electrons starts.

(i) 1s, 2s and 3s-orbitals in Mg-atom are not degenerate orbitals because principal quantum number (n) of these orbitals is different.

(ii) 2px, 2py and 2pz in C − atom are not degenerate orbitals because these orbitals belong to same subshell (i.e. 2p)

(iii) 3s, 3p_x, and 3d orbitals in H-atom are degenerate because for H-atom, the subshells having same value of n have same energies.

Electron is denoted by ‘e’ and is a negatively charged particle. The absolute charge over an electron is equal to 1.6 x 10^-19 of negative charge and is considered equal to –1.

The relative mass of electron is 1/1836. Since the mass of an electron is very small, thus it is considered equal to 0. Electrons revolve round the nucleus of atoms.

Aufbau principle: The lowest energy orbitals are filled first.

Radius of the nucleus = 1.33 x 10^-11 x \(A^{\frac{1}{3}}\)m

Density of nucleus = \(\frac{mass}{volume}\)

= \(\frac{A\times1.66\times10^{-27}kg}{\frac{4}{3}\times\pi\times(1.33\times10^{-11})^3}kg/m^3\)

= Constant

\(\therefore\) The density of nucleus is constant, independent of the element under consideration.

According to Pauli’s exclusion principle, no two electrons of the same atom can have the entire four quantum numbers same.

The arrangement of electrons in shells, subshells and orbitals in an atom is called the electron configuration.

Proton is denoted by ‘p’ and is positively charged particle. The absolute charge over proton is 1.6 x 10^-19 coulomb of positive charge and it is considered as unit positive charge.

Thus absolute charge over a proton is equal to +1.

The absolute mass of a proton is equal to 1.6 x 10 ^-24 g and considered equal to 1 as it is equal to the mass of 1 hydrogen atom. Proton is present in the nucleus of atom.

(i) Charge on one proton = 1.6 × 10⁻¹⁹ C

Number of protons present in He = 2

\(\therefore\) Charge on 2 protons = 2 × 1.6 × 10⁻¹⁹

= 3.2 × 10⁻¹⁹ Coulomb

(ii) Number of protons present in Li = 3

\(\therefore\) Charge on 3 protons = 3 × 1.6 × 10⁻¹⁹

= 4.8 × 10⁻¹⁰ Coulomb

(iii) Number of protons present in C = 6

\(\therefore\) Charge on 6 protons = 6 × 1.6 × 10⁻¹⁹

= 9.6 × 10¹⁹ Coulomb

Most of the alpha particles passed through the foil because most of space in the atom was empty.

Nucleus – The centre of atom is called nucleus. Nucleus comprises of neutron and proton. Nucleus of an atom contains the whole mass of an atom.

Correct answer is (a) Quantitative

Meristematic cells are thin walled, nonvacuolated with prominent nuclei having granular cytoplasm and are capable of cell division.

(c) thin walled, non-vacuolated with prominent nucleus

This is the uppermost layer of the crust and the earth. The mean thickness of Continental Crust around 30km.

Satluj, Beas and water of Ravi.

1. North America

2. Rocky,4800 

3. Mississippi and Missouri 

4. Mackenzie 

5. Lake Ontario 

6. Rio Grand 

7. Superior 

8. Lumbering 

9. sugar bowl of the world” 

10. Soya beans

Seismic Focus: In the inner part of the Earth from where the earthquake originates or the place from where the energy begins to be emitted, is called the Seismic Focus. From this place the energy reaches the Earth’s surface, moving in different directions in the form of waves. 

Epicenter: Located above of the seismic focus (at 90° angle), on the earth’s the first place where earthquake waves reach is called the epicenter. It is located at the closest distance from the seismic focus.

The rivers Satluj and Ghaghar surround the Malwa region.

(a) Nickel and ferrous

The scientific study of soil is called ‘Pedology’.

(i) Waterways are the cheapest means of transport. They are more suitable for carrying heavy and bulky goods. They are a fuel-efficient and environment friendly mode of transport.

(ii) Some waterways have been declared as the National Waterways by the Government:

(a) The Ganga river between Allahabad and Haldia (1620 km) --N.W. No. 1

(b) The Brahmaputra river between Sadiya and Dhubri (891 km)-N.W. No. 2

(c) The West-Coast Canal in Kerala (Kottapurma-Komman, Udyogamandal and Champakkara Canals 205 km-N. W. No. 3).

Arid or desert soils are found in deserts. These soils are formed by wind activities and are sandy in nature. It lacks moisture and humus due to the dry climate and high temperature which causes rapid evaporation. It is infertile and saline due to lack of rainfall. Due to the high quantity of calcium carbonates and sodium, kankar is formed and restricts infiltration of water in the soil.

Black soil or regur soil is found in the Deccan Plateau in India. It is a soil formed by the flow of lava. These soils have a rich black colour due to the abundance of lime, iron, magnesium, aluminium, and potassium. It has a clayey texture which is likely influenced by the climate. It has a high water retaining capacity, swells to become sticky due to monsoons and develops fracks when it is dry.

(i) Ferrous: Iron and Manganese

(ii) Non-ferrous: Copper and Lead

(iii) Light metal: Aluminium

(iv) Rare metals: Zirconium

Cyclone depressions coming from Mediterranean Sea called Western Disturbances and cause low to moderate rainfall over northern India. This rainfall is boon to the wheat crop which is generally cultivated in ‘Rabi’ season.

Correct option is C) Wheat

Correct option is A) 30 years

Answer is (B) Red

Answer is (B) Black

A) Sandy coastal

D) All the above

(C) West Godavari

(D) Ananthapur

(B) moderate

Answer is (C) high

Correct option is B) January