COMEDK Mock Test - 6 - JEE MCQ

Increase in length,

∴

The thermal stress developed,

or,

From FBD of one part of the wheel, F = 2T, where F is the force that one part of the wheel applies on the other part.

∴ F =

where ф = W = Flux x Per unit turn of the coil

Total resistance of the coil and the meter = R + 4R

Therefore,

l = 25.0 cm
Time of 40 oscillations is 50 sec.

We know that,
R = R₀A^1/3

⇒ Straight line

⇒ Q - 2q = 0
⇒ Q = 2q

An atom based on the classical theory of Rutherford's model should collapse as the electrons in continuous circular motion, that is a continuously accelerated charge, should emit EM waves and so should lose energy. These electrons losing energy should soon fall into heavy nucleus collapsing the whole atom.

Explanation:

for monoatomic gas 

from conservation of energy

The maximum kinetic energy for the photoelectrons is 
E_max​=hν−ϕ
where, ν is the frequency of incident light and ϕ is photoelectric work function of metal.
eV_0​=hν−ϕ ...................(1)
where, V₀​ is the stopping potential and e is the electronic charge.
When, the frequency of light in a photoelectric experiment is doubled, 
eV₀′​=2hν−ϕ 
eV₀′​=2[hν−(ϕ/2​)].........................(2)
From the above two equations we can say that the K.E. in (2) is more than double of K.E in (1). Hence, when the frequency of light in a photoelectric experiment is doubled, the stopping potential becomes more than double.
So, the answer is option (C).
 

Mass, m = 14.5 kg
Length of the steel wire, l = 1.0 m
Angular velocity, ω = 2 rev/s = 2 × 2π rad/s = 12.56 rad/s
Cross-sectional area of the wire, a = 0.065 cm² = 0.065 × 10^-4 m²
Let Δl be the elongation of the wire when the mass is at the lowest point of its path.
When the mass is placed at the position of the vertical circle, the total force on the mass is:
F = mg + mlω²
= 14.5 × 9.8 + 14.5 × 1 × (12.56)²
= 2429.53 N
Young’s modulus = Strss / Strain
Y = (F/A) / (∆l/l)
∴ ∆l = Fl / AY
Young’s modulus for steel = 2 × 10¹¹ Pa
∆l = 2429.53 × 1 / (0.065 × 10^-4 × 2 × 10¹¹)   =   1.87 × 10^-3 m
Hence, the elongation of the wire is 1.87 × 10^–3 m
Hence 1.87 × 10^–3 m

Position vector of box and stone are 

When stone hits the block,

= 9.8 m

For ball A, The velocity of the ball before entering the water surface is 

When ball enters into the water, due to Upthrust of water the velocity of ball decrease (retarded). 

If h be the depth up to which ball sink, then v² - u² = 2as

For ball  B, The velocity of the ball before entering the water surface is 

When ball enters into the water, due to Upthrust of water the velocity of ball decrease (retarded).
So retardation,

If h be the depth up to which ball sink, then v² - u² = 2as

Ratio of the depth of ball 

d_A−B = r_A + r_B − 0.09(x_A − x_B) = 6 − 0.09(1.9) ≈ 5.829

The smaller the atomic size, larger is the value of ionization potential. Further the atoms having half filled or fully filled orbitals are comparatively more stable, hence more energy is required to remove the electron from such atoms.

According to Gibb's equation:

The reaction becomes spontaneous at a temperature at which  is a negative value.
At 298K:

Since ΔGº is positive, the reaction is not spontaneous at this temperature.



Hence, the reaction is spontaneous above 1100 K or 827^oC.

• This option is correct because both the statements A and B are incorrect.
• Trans-dichloro bis (ethylenediamine) rhodium(III) is symmetrical and therefore, is optically inactive.
• According to Werner's theory, secondary valency is directional, whereas primary valency is non-directional.
• Geometrical isomers are possible for [Co(en)₂Cl₂]⁺ and the cis isomer is optically active.

In the alkaline medium, the permanganate ion is reduced to manganate ion by the transfer of 1 electron as follows:

1, 2-dibromoethane (ethylene dibromide) is added to petrol to prevent lead deposition, which occurs by decomposition of the anti-knock lead tetraethyl bromomethane.

Required ways = 4 x 4 x 4 x 4 x 4 = 4⁵

The determinant of skew-symmetric matrix of odd order is always zero
Therefore the inverse of skew-symmetric matrix does not exist