Explore topic-wise InterviewSolutions in Current Affairs.

Correct answer is: (a) Ida Bengston

Industries like milk products, cider, cocoa, pickles, pharmaceuticals depend on Lactobacilli bacteria.

The answer is (b) It reacts with cold water to form magnesium oxide and evolves hydrogen gas.

Magnessium reacts with cold water to form magnesium oxide and evolves hydrogen gas is a wrong statement because Magnessium Hydroxide is formed not Magnessium oxide.

Correct answer is: (b) Clostridium

Cottage industries like the manufacture of milk products like ghee, cheese, paneer, curd, shrikhand, etc. and chocolate making can be started in areas with abundant milk production.

Plant diseases:

• Citrus canker is a bacterial disease that affects 1 trees of citrus fruits.
• Rust of wheat is a fungal disease that affects wheat crops.
• Yellow vein mosaic is a viral disease which affects vegetables like bhindi (okra).

Preventive Measures:

• Seeds which are healthy and disease-free should be selected for sowing. 
• Infected plants should be removed. 
• Plants should be sprayed with fungicides and germicides to prevent diseases.

Animal diseases:

• Anthrax is a disease that affects cattle. 
• It is caused by a bacterium. Foot and mouth is a dangerous disease in cattle caused by a virus.
• Rabies is a viral disease that affects animals.

Preventive Measures:

• The place where animals are kept should be washed with germicides. 
• Animals should be dewormed regularly. 
• The animals should be treated with necessary antibiotics for infectious diseases. 
• They should be regularly vaccinated. 
• Take the animals to a veterinary hospital for proper treatment and vaccination.

Correct answer is: (c) Lactobacilli

Magnesium ribbon burns with dazzling white light, once treated to its ignition temperature. The white powder formed is Magnesium oxide which dissolves in water to give a basic solution which turns red litmus blue. Thus 'x' is Mg and 'y' is MgO.

2MgO+O₂ → 2MgO

MgO+H₂O → Mg(OH)₂

D) Fe + CuSO₄ → FeSO₄ + Cu

• Fungi decompose the bodies of dead animals and convert them into simple carbon compounds. These substances easily mix with air, water and soil from where they are again absorbed by plants and enter the food chain. 
• Some fungi living in symbiotic association with plants help to absorb water and inorganic compounds like nitrate and phosphate. 
• Fungi are also used to derive antibiotics like penicillin which are useful to animals.
• Ants grow fungi in their anthill and obtain food from it. 
• Some species of wasps and insects lay their eggs in the fungal bodies growing on trees, thus ensuring a food supply for their larvae.

A simple reactant breaks down to give simpler products and the process is known as decomposition reaction.

Example: CaCO₃(s) + Heat → CaO(s) +CO₂(g)

CaO(s)-Quick lime

MnO₂ + 4HCI → MnCl₂+ 2H₂O+Cl₂ 

• Lichen is a symbiotic association between a fungus and an algae (Cyanobacterium). 
• Lichens are sensitive to environmental disturbances and are used in assessing air pollution in an area. 
• Lichens are also used in making dyes, perfumes and in traditional medicines. 
• A few lichen species are eaten by insects or animals such as reindeer.

L – shell is at higher energy level, because it is far from nucleus than K shell.

Option : (D) three, four

An orbital is designated by three quantum number (n , l , m) while an electron in an atom is designated by four quantam number (n , l , m and s)

Option : (D) three, four

Tomato - Malic acid and citric acid

Strong acid: An acid which dissociates completely in water and produces a large amount of hydrogen ions. e.g., HCl.

Weak acid: An acid which dissociates partially in water and produces a small amount of hydrogen ions. e.g., CH₃COOH.

Electron spin quantum number (m_s) :

• Electron spin quantum number describes the spin state of the electron in an orbital. It is designated as ms.
• An electron spins around its axis and this imparts spin angular momentum to it.
• The two orientations which the spin angular momentum of an electron can take up give rise to the spin states which can be distinguished from each other by the spin quantum number, m_s, which can be either +1/2 or -1/2.
• The two spin states are represented by two arrows, ↑ (pointing up) and ↓ (pointing down) and thus have opposite spins.

n = 2 and l = 1

Correct option is  A) Cs

For the 4s orbital, 

4 stands for the principal quantum number n; s stands for the subshell s having the value of azimuthal quantum number, l = 0. 

In the ‘s’ subshell, there is only one orbital and has magnetic quantum number, m_l = 0. 

The two electrons in this orbital have opposite spins. 

Thus, 

The four quantum numbers of two electrons in 4s orbital are :

Bromine (Atomic No. 35) = 1s² 2s² 2p⁶ 3s² 2p⁶ 3d¹⁰ 4s² 4p⁵

2p orbital has 6 electrons.

3p orbital has 6 electrons and 4p orbital has 5 electrons.

4p electron experience lowest effective nuclear charge because of the maximum of screening or shielding effect.

v = 4.37 x 10⁵ ms^-1

m = 0.1 kg

h = 6.626 x 10^-34 Js

λ = h/mv

or, λ = {6.626 x 10^-34}/{10^-1 x 4.37 x 10⁵}

or, λ = 6.626/4.37 x 10^-38 = 1.51 x 10^-38 m.

(i) Represents 4d orbital (ii) Represents 3d orbital, (iii) Represents 4p orbital (iv) Represents 3d orbital (v) Represents 3p orbital (vi) represents 4p orbital

3p < 3d < 4p < 4d

Combination (2) n = 3, l = 2, m₁ = 1, m_s = +1/2 and combination (4) n = 3, l = 2, m₁ = -2 and m_s = -1/2 have the same energy lists.

Similarly combination (3) n = 4, l = 1, m₁ = 0, and m_s = 1/2 and combination (6) n = 4, l = 1, m₁ = 0, m_s = +1/2 have the same energy lists.

Therefore, (v) < (iii) = (iv) < (vi) = (iii) < (i)

In order to define state energy and location of electron a set of four numbers is used. These numbers are called quantum numbers. 

• Principal quantum number (n) 

• Azimuthal quantum number (1) 

• Magnetic quantum number (m) 

• Spin quantum number (s).

The energy emitted by an electron is seen in the form of an electromagnetic energy and when the wavelength is. in the visible region it is visible as an emission line.

If the position of the electron is known with high degree of accuracy (Δ_x is small), then the velocity of the electron will be uncertain (Δ(V_x) is large.)

According to de Broglie’s relation, λ = h/mv ie λα1/m of the car is very large and its wavelength (λ) or wave character is negligible. Therefore, we do not see a car moving like a wave.

Angular nodes occur when the probability density wave function for the electron is zero along the directions specified by a particular angle. Number of angular nodes = l

Total number of nodes = n – 1

Electronic Configuration:

Cl⁻ = 2, 8, 8 = 1s² , 2s²2p⁶ , 3s²3p⁶

O²⁻ = 2, 8 = 1s² , 2s²sp⁶

Since last electron of Cl⁻ occurs in 3p sub- shell and last electron of O²⁻ occurs 2p subshell. As we know that, according to Aufbau principle, 3p Subshell has more energy than 2p subshell. Therefore, last electron of Cl⁻ has more energy of electron.

(ii) n = 4, l = 3 represent 4f

n = 5, l = 2 represents 5p

According to Aufbau principle, the energy of 4f is more than 5p. So, n = 4, l = 3 has more energy of electron.

Carbon with atomic number 6, shows electronic configuration 2, 4. Silicon with atomic number 14 shows electronic configuration 2, 8, 4. 

Both the elements have same valence electrons, hence they are placed in same group.

(i) When n = 1, value of l cannot be equal to 1. Thus it is not possible.

(ii) Value of n i.e., shell starts from 1 and not from zero. Thus, it is not possible.

Radial nodes occur when the probability density of wave function for the electron is zero on a spherical surface of a particular radius. 

Number of radial nodes = n – l – 1. 

The electron moves to higher energy level called the excited state

Distribution of electrons in chloride ion are: -

Chlorine ion - K shell: 2 electrons

L shell: 8 electrons

M shell: 8 electrons

Hence, the number of valence electrons in chloride ions are 8 as its outermost orbit
contains 8 electrons.

The electron loses the energy and comes back to its ground state. The energy emitted by the electron is seen in the form of electromagnetic energy.

a – iv, 

b – iii, 

c – ii, 

d – i

Correct option is d. 6 x 10¹⁴ Hz

The representation of the given element is \(^{11}_5X\).

Wave length (λ) = 100 mm

= 100 x 10^-9 m = 10^-7 m  

Speed of light (c) = 3 x 10⁸ m/s

We know c = vλ ⇒v = c/λ = 3 x 10⁸/ 10^-7 

= 3 x 10¹⁵ Hertz.

Light can be characterized by its wavelength and frequency (v) and these quantities related to the speed of light as c = vλ

No, Bohr’s model failed to account for splitting of line spectra

It looks very big in size, and it is difficult to identify, as these elements have similar properties.

A spectrum is a group of wavelengths.

1. The energy required to remove an electron from unipositive ion is called second ionisation energy. 

2. It is difficult to remove an electron from unipositive ion when compared with neutral atom due to an increase in nuclear attraction. 

3. So always second ionisation energy is higher than first ionisation energy.

Given that the Mass number of the atom is 27.

⇒ Number of protons + number of neutrons = 27

⇒ Number of protons + 14 = 27

⇒ Number of protons = 13

Therefore, number of electrons in a neutral atom = 13

The ion of the element has 3 positive charges.

⇒ Number of electrons = 13 – 3 = 10

Hence, option B is correct.

(1) Excitation energy of an electron in an atom : The energy required to transfer an electron from the ground state to an excited state (a state of higher energy) is called the excitation energy of the electron in that state.

(2) Binding energy of an electron in an atom is defined as the minimum energy that should be provided to an orbital electron to remove it from the atom such that its total energy is zero.

(3) Ionization energy of an electron in an atom is defined as the minimum energy required to remove the least strongly bound electron from a neutral atom such that its total energy is zero.