Explore topic-wise InterviewSolutions in Current Affairs.

The correct option is a 

According to the given figure, A⁺ is present in the octahedral void of X⁻ The limiting radius in the octahedral void is related to the radius of the sphere as

r_void= 0.414sphere

r_A = 0.414r

=0.414 × 250pm

=103.5

 = 104 pm

The correct answer is increased collision frequency of X with the inert gas as compared to that of Y with the inert gas

• X is a lighter gas than Y, hence X  has greater molecular speed. 
• Due to the greater molecular speed of X, it will have a smaller mean free path and greater collision frequency with the inert gas molecules. 
• As a result, X will take more time to travel a given distance along a straight line.
• Hence X and Y will meet at a distance smaller than one calculated from Graham's law

ΔT_f = i x m K_f

0.2 = 2 x 2 x (w/58.5)/(600/1000)

w = 1.755gm

ΔT_f = 0.2 = 2 x n/600 x 1000 x 2

n = 0.1 x 0.6/2 = 0.03moles

mass of Nacl = 0.03 x 58.5

= 1.755

The correct option is (b) Full wave.

Transistor is used to convert full wave

A transistor is used in an amplfier and if it is properly biased and can be used as an oscilator when the gain of the amplifier is infinite. Therefore it can convert its dc power into an ac full cycle and it has frequency according to its components values like f depends on L and C.

Answer given below:

https://bit.ly/2vP9wMF

We know that,

The mass is physical quantity of an object which is independent of gravitational force. so it will remain same on the moon.

Correct option is (2) One more capacitor is connected in series with C

\(\omega_r = \frac1{\sqrt{LC}}\), to increase \(\omega_r\), the capacitance is to be decreased.

Correct option is (C) Another capacitor should be added in series with the first capacitor

\(f = \frac1{2\pi\sqrt{LC}}\)

To increase the resonating frequency product of L and C should decrease. 

By joining capacitor in series, capacitor will decrease

The wavelength of emitted series is 99.2nm and this belongs to the Lyman series of Bohr's Hydrogen spectrum.
The wavelength of series emitted during transition is given by the formula.
hc/E=1
E=12.5eV
hc=1240eV
Therefore wavelength of emitted series is:
I=1240/12.5=99.2nm
This belongs to the Lyman series of Bohr's Hydrogen spectrum.

we know the energy of electron in n th orbit of Hydrogen

E_n = -K/n^2ev, k = constant

So the difference in the energy of the electron in n=2 and n=3 orbits is

E = E₃ – E₂  = -K[1/3^2-1/2^2] = K*5/36

=>K = 7.2E

Now ionization energy of hydrogen atom is the energy required to promote electron from n=1  to n= ∞

So This ionization energy = -K{1/∞^2-1/1^2]=K =7,2E

Hence option (B) is accepted

Correct option is (A) In primary rainbow, observer sees red colour on the top and violet on the bottom

In primary rainbow, red colour is at top and violet is at bottom. Intensity of secondary rainbow is less in comparison to primary rainbow.

 (b) 12Ω

Explanation:

Series connection = R₁ + R₂

equivalent resistance = R = R₁ + R₂

 = (100 ± 5) + (200 ± 7)

= 300 ± 12Ω

 maximum absolute error = 12Ω 

(c) 2a + b

Explanation:

T = 2π √(ℓ/g)

 ∴        T² = (2π)²(ℓ/g)

  ∴        g = [(4π²ℓ) / (T²)]

(Δg / g) = (Δℓ / ℓ) + 2 (ΔT / T)

    = b + 2a 

y = tan^-1(\(\frac{cos x - sin x}{cos x + sin x}\))

 = tan^-1(\(\frac{1-tan x}{1+tan x}\)) (On dividing numerator and denominator by cos x)

 = tan^-1(\(\frac{tan \pi/4-tan x}{1+tan \pi/4 tan x}\))

 = tan^-1(tan(\(\pi/4-x\)))

 = \(\pi/4-x\)

\(\therefore\) \(\frac{dy}{dx}=\frac{d}{dx}(\frac{\pi}4-x)=-1\)

 (a)  3(Δr / r)

Explanation:

V = (4/3)πr³

 (ΔV / V) = 3(Δr / r)   

(√3 + √2)x - (√2 - √5)y = 0 -----(1)

(√2 - √5)x + (√3 + √2)y = 0---(2)

Multiplying equation (1) by (√3 + √2) & equation (2) (√2 - √5), we get

(√3 + √2)²x - (√3 + √2) (√2 - √5)y = 0---(3)

(√2 - √5)²x + (√3 + √2) (√2 - √5)y = 0---(4)

By adding equation (3) and (4) we get

((√3 + √2)² + (√2 - √5)²)x = 0

⇒ x = 0

(\(\because\) (√3 + √2)² > 0 &  (√2 - √5)² > 0 ⇒ (√3 + √2)² + (√2 - √5)² \(\neq0\))

Put x = 0 in equation (2) we get

(√3 + √2)y = 0

⇒ y = 0 (\(\because\) \(\sqrt3+\sqrt2\neq0\))

Hence, solution of given system of equations is x = 0, y = 0

\(4x +\frac{y}{3} =\frac {8}{3}\)

⇒ 12 x + y = 8  — (1) ( on multiplying both sides by 3)

and \(\frac{x}{2}+\frac{y}{4}=-\frac{5}{2}\)

⇒ 2x + y = -10 — (2) ( on multiplying both sides by 4)

subtract equation (2) from (1) , we get

(12x+y) - (2x+y) = 8 - (-10)

⇒ 10x = 18

⇒ x = \(\frac{18}{10}=\frac{9}{5}\)

∴ from (2), we obtain

\(\frac{18}{5}+y=-10\)

⇒ y = -10 - \(\frac{18}{5}\) = \(\frac{−50−18}{5}=\frac{−68}{5}\)

A quadratic equation ax² + bx + c = 0 has no real root if 

D < 0, where D is discriminant

b² – 4ac < 0.

Correct option  (A) c/a 

Explanation:

Given quadratic polynomial ax² + bx + c zeroes = α and  β.

∴  product of roots = constant term/coefficient of  x²

α . β = c/a.

Correct option  (a)  ±√3

Explanation:

Given polynomial x² – 3

zeroes of x² – 3

x² – 3 = 0 

x² = 3

Taking square root both sides.

x =  ±√3

Given sum of zeroes = – 3

product of zeroes = 3

We know quadratic polynomial 

= x² – (sum of zeroes) x + (product of zeroes)

= x² – (– 3)x + (2) 

= x² + 3x + 2

(b) 1,2,–1

Explanation:

centripetal force =(mv² / r) = mv²r^–1

 hence a = 1, b = 2, c = – 1 

There are always two parallel tangents about a diameter.

Correct answer is (b) R/√(R² + W² L²)

B. Allopurinol

Microsomal enzyme induction can be a cause of Tolerance.

Velocity of light, c = \(\frac{1}{\sqrt{\mu_0\varepsilon_0}}\)

µ₀ = Permeability of free space, 

∈₀ = Permittivity of free space.

Difference between DC series and DC shunt motor:

Working principle of shunt motor:

When we apply a voltage to the motor a current produced in the armature and a strong magnetic field, by the way, produced this field interacts with the magnetic field and makes the armature rotates. When the armature rotates it produces a back EMF this EMF opposes the armature voltage and reduces the armature current if we increase the motor load the armature will rotate slowly and the back EMF will reduce.

The phenomenon of bending of light around the comers of (edges of) small obstacles or apertures and spreading into geometrical shadow region is called diffraction of light.

Some properties of X -rays.

(i) They can under go reflection,refraction interference diffration and position.

(ii) They effect photo- graphic plates.

Lenz's law states that the direction of induced current is such that it opposes the cause which produces it. It is based on the law of conservation or energy.

In 1875 Focault observed that when a metal piece is kept in variable magnetic field, currents are always induced in the plate which is of whirting nature they are called Eddy current.

p-type: 

(i) p-type semiconductor is obtained by doping a trivalent impurity to a pure semi conductor.

(ii) Number of holes is greater than number of electrons i.e. n_h > n_e 

(iii) holes-majority carriers. 

(iv) electrons-minority carriers. 

(v) trivalent doping provides one hole for conduction. 

(vi) Impurity is called acceptor type.

n-type: 

(i) n-type semiconductor is obtained by doping a pentavalent impurity to a pure semiconductor. 

(ii) Number of holes is less than number of electrons n_h < n_e 

(iii) holes-minority carriers. 

(iv) electrons-majority carriers. 

(v) Pentavalent doping provides one extra electron for conduction. 

(vi) Impurity is called donor type.

The phenomena of complete reflection of light at the interface of two optical media when a ray of light travelling in denser medium is called total internal reflection.

(i) Optical fibre are used in telecommunication 

(ii) It is used to measure rate of flow of blood.