Explore topic-wise InterviewSolutions in Current Affairs.

Answer is NaCN

1. Mass of organic compound (W₁) = 0.2562g 

2. Mass of AgBr obtained (W₂) = 0.2632g.

Electronic Concept of Oxidation and Reduction

Oxidation: The process in which there is loss of electrons.

Reduction: The process in which there is gain of electrons.

On fusing with sodium metal the elements presents in an organic compounds are converted in to sodium salts which are water soluble which can be filtered and detected by the respectivetests.

Lead acetate on reacting with sulphuric acid will give a white ppt of lead sulphatewhih interfere in the detection of sulphur.

(CH₃COO)₂Pb +H₂SO₄ → PbSO₄+ 2CH₃COOH

1. Mass of organic compound taken (W₁) = 0.189 g 

2. Mass of AgCli ppt (W₂) = 0.287 g

It is also estimated by carius method the known mass of organic compound containing phosphorus is heated with fuming HNO₃ when phosphorus is oxidised to phosphoric acid (H₃PO₄). To this, magnesia mixture (MgSO₄ + NH₄OH + NH₃Cl) is added when phosphoric acid precipitates as magnesium ammonium phosphate (MgNH₄PO₄). This precipitate is filtered, washed, dried and ignited when it is converted to magnesium pyrophosphate (Mg₂P₂O₃).

The weight of Mg₂P₂CO₇ is determied from which the percentage of phosphorus is the compound can be calculated. Observations and Calculations: 

1. Mass of organic compound taken = w₁, g. 

2. Mass of Mg₂P₂O₇ obtained = W₂g. 

We have contains 62g of phosphorus.

W₂g of Mg₂P₂O₇ Will contain \(\frac{62\times w_2}{222}\)g of phosphorus 

This amount of phosphorus was present in wig of the compound

∴ %P = \(\frac{62\times w_2}{222}\) x \(\frac{100}{w_1}\)

(i) Na₂[Fe(CN)₅NO] 

(ii) Fe₂[Fe(CN)₆]₃

Halogen containing organic compounds but some other compounds like urea is respond to this test.

Demerits of Bohr’s atomic model :

• Bohr’s atomic model (theory) failed to account for finer details of the atomic spectrum of hydrogen as observed in sophisticated spectroscopic experiments.
• Bohr’s atomic model (theory) was unable to explain the spectrum of atoms other than hydrogen.
• Bohr’s atomic model (theory) could not explain the splitting of spectral lines in the presence of a magnetic field (Zeeman effect) or electric field (Stark effect).
• Bohr’s atomic model (theory) failed to explain the ability of atoms to form molecules by chemical bonds.

Postulates of Bohr’s theory of hydrogen atom : 

i. The electron in the hydrogen atom can move around the nucleus in one of the many possible circular paths of fixed radius and energy. 

These paths are called orbits, stationary states or allowed energy states. 

These orbits are arranged concentrically around the nucleus in an increasing order of energy.

ii. The energy of an electron in the orbit does not change with time. 

However,

The electron will move from a lower stationary state to a higher stationary state if and when the required amount of energy is absorbed by the electron. 

Energy is emitted when electron moves from a higher stationary state to a lower stationary state. 

The energy change does not take place in a continuous manner.

iii. The frequency of radiation absorbed or emitted when transition occurs between two stationary states that differ in energy by ΔE is given by the following expression :

ν = \(\frac{vE}{h}=\frac{E_2-E_1}{h}\) ………….(1)

Where E₁ and E₂ are the energies of the lower and higher allowed energy states respectively. 

This expression is commonly known as Bohr’s frequency rule.

iv. The angular momeñtum of an electron in a given stationary state can be expressed as mvr = n × h/2π

Where, n 1,2, 3

Thus,

An electron can move only in those orbits for which its angular momentum is integral multiple of h/2π.

Thus,

Only certain fixed orbits are allowed.

Characteristics of electromagnetic radiations: 

Wavelength: It may be defined as the distance between two neighbouring crests or troughs of wave as shown. It is denoted by λ. 

Frequency (ν): It may be defined as the number of waves which pass through a particular point in one second.

Velocity (v): It is defined as the distance travelled by a wave in one second. In vacuum all types of electromagnetic radiations travel with the same velocity. Its value is 3 x 10⁸ m sec^-1. It is denoted by v

Wave number: Wave number (bar v) is defined as the number of wavelengths per unit length.

Velocity = frequency x wavelength c = νλ

Cosmic rays < X-rays < amber colour < microwave < FM.

Correct option is d. four nodes

wave length = C/V₀ = 3x 10⁸ /5.09x10¹⁴ 

= 5.89 x10^-7 meter

1. An orbit is a well defined path of electron that revolves around the nucleus.

2. An orbital is the space around the nucleus, where the probability of finding electrons is maximum.

Correct option is A) absorb

(a) Atomic no. is the number of protons in one atom of an element. 

Mass no. is the total number of protons and neutrons present in one atom of the element.

Example- The total no. of protons in a carbon atom is 6, so its atomic no. is 6. 

Also, one atom of Na contains 11 protons and 12 neutrons, so its mass no. is 23. 

(b). Mass No. = Atomic no. + No. of neutrons 

(c). No. of neutrons = Mass No. – Atomic no. 

= 24 – 12 = 12

The properties of cathode rays are:

1. cathode rays are negatively charged particles 

2. cathode rays are a stream of particles which travels in straight line. 

3. Cathode rays can effect a photographic plate

It is because we need high energy radiation to see an electron which change the velocity of electron.

(a) Bohr Model of atom: 

An atom is made up of three particles: Electrons, neutrons and protons. 

1. The protons and neutrons are located in a small nucleus at the centre of atom 

2. The electrons revolve rapidly around the nucleus at the centre of the atom 

3. There is a limit to the number of electrons that each energy level can hold 

4. Each energy level is associated with a fixed amount of energy. 

5. There is no change in the energy of electrons as long as they keep revolving in the same energy level. 

Bohr explained the stability through the concept of revolution of electrons in different energy levels. The change in the energy of an electron occurs when it jumps from lower to higher energy levels. When it gains energy, it excite from lower to higher and vice versa. Thus energy is not lost and the atom remains stable. 

(b) Given: 

Atomic no. = 11 

Mass no. = 23 

Then, electronic configuration – (2,8,1) 

Nuclear composition is – 11 protons and 12 neutrons

D) both B & C

A) P – y, Q – z, R – x

Absorption spectrum: The spectrum formed by the absorption of energy when electron jumps from lower energy level to higher energy level is called absorption spectrum. It contains dark lines on bright background.

Significance of three quantum numbers in predicting the positions of an electron in an orbit. 

1) Principal quantum number (n) : 

The principal quantum number explains about the size and energy of shells (or) orbitals. It is denoted by n. 

As ‘n’ increases, the orbitals become larger and the electrons in those orbitals are farther from the nucleus.

It takes values 1, 2, 3, 4, ……………. for that the shells are represented by letters K, L, M, N, ……….

The number of electrons in a shell is limited to 2n²

2) The Angular – momentum quantum number (l) : 

The angular momentum quantum number defines the shape of the orbital occupied by the electron and the orbital angular momentum of the electron, is in motion.

l takes values from 0 to n – 1 for these values the orbitals are designated by letters s, p, d, f, ………….. etc. 

l also governs the degree with which the electron is attached to nucleus. The larger the value of l, the smaller is the bond with which it is maintained with the nucleus.

3) Magnetic orbital quantum number (m ) : 

The orientation of orbital with external magnetic field determines magnetic orbital quantum number. 

m_| has integer values between – l and l including zero. 

The number of values for m, are 2l + l, which give the number of orbitals per sub-shell. The maximum number of electrons in orbitals in the sub-shell is 2 (2l + l).

D) stability of the atom

C) same valency

When soap is dissolved in water, its hydrophobic ends attach themselves to dirt and remove it from the cloth.

First, the molecules of soap arrange themselves in micelle formation and trap the dirt at the centre of the cluster.

These micelles remain suspended in water like particles in a colloidal solution.

The various micelles present in water do not come together to form a precipitate as each micelle repels the other because of the ion-ion repulsion.

Thus, the dust particles remain trapped in micelles (which remain suspended) and are easily rinsed away with water.

 Hence, soap micelles remove dirt by dissolving it in water.

Correct option is D) nucleus

1. Rainbow is a spectrum of different colours (VIBGYOR) with different wavelengths. 

2. These colours are continuously distributed. 

3. There is no fixed boundary for each colour. 

4. Hence, rainbow is a continuous spectrum.

Sommerfeld added two elliptical orbits to Bohr’s third orbit.

Purpose of adding elliptical orbits : 

1. Bohr’s model failed to account for splitting of line spectra and line spectrum. 

2. In an attempt to account for the structure of line spectrum, Sommerfeld modified Bohr’s atomic model by adding elliptical orbits.

D) both A & B

The metals having large size and less work function are used in photo electriccell.eg. Li

Balmer series of lines of the hydrogen spectrum lies in the visible regio

\(|\psi|^2\) show the probability of finding the electron at a point with coordinates (x, y, z).

Ψ² represents probability of finding an electron.

Physical significance of ψ: All the information about the electron in an atom is stored in its orbital wave function ψ and quantum mechanics makes it possible to extract this information out of ψ.

Physical significane of ψ²: From the value of | ψ|² at different points with in an atom, it is possible to predict the region around the nucleus where electron will most probably be found.

ψ² represent probability of finding an electron.

C) both A and B

A) a → iv, b → i, c → ii, d → iii

This is because the energies of the orbits in which the electrons revolve are fixed.

This means that the electrons in an atom have only definite values of energies.

Lyman Series

The rule violated is Hund’s rule.

Correct option is  C) Aufbau principle

Correct option is  A) Aufbau

C) Erwin Schrodinger

According to the electromagnetic theory of Marwells, charged particles when accelerated should emit electromagnetic radiation. Therefore, an electron in an orbit will emit radiation; the orbit will then continue to shrink which does not happen in an atom.