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B) hypermetropia

Correct option is  B) biconcave

C) ciliary muscles

(a) ciliary muscles

The least distance of distinct vision for a young adult with normal vision is about 25cm

Correct option is  A) myopia

A is copper sulphate pentahydrate, CuSO₄ .5H₂O

B is water, H₂O

C is anhydrous copper sulphate, CuSO₄

D is water, H₂O

(c) ciliary muscles.

The ability of eye to see nearby as well as far off objects at the same time is called power of accommodation.

Correct option is  B) near point

The ability of the eye lens to adjust its focal length is called the power of accommodation. 

The focal length of the eye lens is adjusted so that the image distance does not change. Thus the image distance is equal to the distance from the center of the eye lens to the retina.

Myopic Person does not need spectacles while reading a book as he has the near point at 25 cm. If such person reads the book with corrective lens (concave) he will have to keep the book at a distance greater than 25 cm so that the image of the book will be formed by the concave lens at 25 cm and moreover the size of the book that appears to him is also smaller. Therefore, the person prefers to remove his spectacles while reading a book.

(a) A myopic person does not need spectacles while reading a book as he has the near point at 25 cm. If such person reads the book with corrective lens (concave) he will have to keep the book at a distance greater than 25 cm so that the image of book will be formed by the concave lens at 25 cm and moreover, the size of the book appears to him is also smaller then actual size. Therefore, the person prefer to remove his spectacles while reading a book. 

(b) A hypermetropic person does not need spectacles to see distant objects as he has the far point at infinity. If such person uses spectacles (convex lens) to see the distant objects, the image will be formed before the retina due to increase in converging power and hence the person cannot see distant objects distinctly. Therefore, such person prefers to remove his spectacles while looking at the sky.

Cl: This is because the ionization enthalpy decreases from F to Cl as we move down the group of halogens in the periodic table. The decrease in ionization enthalpy is due to increase in atomic size of the atoms. The atom with a bigger size requires comparatively less energy to remove the electron. Hence, the first ionization enthalpy of chlorine is lower as compared to that of fluorine.

K: Potassium has a lower value of first ionization enthalpy than argon. This is because Argon, an inert gas, has fully filled valence orbital from which electrons cannot be removed easily.

S: Sulphur has a lower value of first ionization enthalpy as compared to chlorine. This is because on moving along a period from left to right the atomic size decreases and hence ionization enthalpy increases. Sulphur has a bigger size and hence lower value of its first ionization energy.

1. For distant vision: 

P = -5.5D 

P = 1/f 

f = 1/P = 1/(-5.5) 

= -0.1818 m = -18.18cm 

2. For Near Vision: 

P = 1.5D P = 1/f 

f = 1/P = 1/1.5 = 0.6666 = 66.66 cm

A hypermetropic eye can have a normal far point. If he uses spectacles of the converging lens, he will have more converging power than needed for parallel rays so the distant object may get focused in front of the retina and so distant objects will appear blurred.

The ionization energy.

(a) Decreases in going from top to bottom in a group.

(b) Increases in going from left to right in a period.

Thus

(i) Cl is below F in the group (or Cl is bigger than F), hence Cl has lower ionization energy than F.

(ii) Cl is in the group 17th, while S belongs to 16th group (of the same period, Period 3). Thus, S should have lower ionization due to lower nuclear charge.

(iii) K appears immediately after Ar in the periodic table. K belongs to group 1 of the periodic table; hence K should have lower ionization energy.

(iv) Xe occurs below Kr in group 18 of the periodic table, hence Xe should have lower ionization energy due to its larger size.

(i) Concave mirror (ii) Near point or 25 cm.

Astigmatisrn.

It can be corrected by using spectacles with a concave lens of suitable focal length.

Myopia (or) nearsightedness is caused by 

• excessive curvatures of the eye| 
• elongation or increase in the size of the eye lens.

(c) Nitroso benzene

(a) Azo benzene

(a) 1, 3 – dinitro benzene

Correct option is (A) angle of deviation due to reflection.

Correct option is (B) i = 0° then r = 0°

Correct option is (B) π

Correct option is (B) is blocked by second polaroid

Characteristics of wave normal:

i. It gives the direction of propagation of wave.

ii. It is perpendicular to wavefront.

iii. In a homogeneous isotropic medium, wave normal is same as direction of ray of light.

iv. It is drawn from the point of generation of wavefront.

Characteristics of wavefront:

i. Wavefronts travel with the speed of light in all directions in an isotropic medium.

ii. The phase difference between any two points in the same phase on the two consecutive wavefronts is 2π. So, if the phase at a crest is 2π, then phase at next consecutive crest = 4π and so on. Hence at any crest, the phase is 2nπ and phase at any trough is (2n + 1)π, where n is an integer.

iii. It always travels in the forward direction. During the propagation of spherical wavefront from a source, wave becomes weaker. It is so because same energy is distributed over circumference of larger circles of increasing radii.

iv. In anisotropic medium, it travels with different velocities in different directions due to variation in densities of the medium.

Uses of Polaroids:

i. Polaroids are used in motor car head lights to remove head light glare.

ii. Used in three dimensional movie cameras.

iii. They are used to produce and analyse polarised light.

iv. They are used as filter in photography.

v. They are used in window of aeroplanes to control amount of light.

vi. Used in polarising sunglasses (goggles) to protect the eyes from glare of sunlight.

vii. They are used to improve colour contrast in old oil paintings.

viii. They are used in calculators, watches, monitors of laptops which have LCD screens.

Correct option  (B) Plate b 

Explanation:

As the magnet is moving away from the conducting loop, the magnetic flux associated with the loop weakens. Thus an e.m.f. will be induced in the loop to strengthen the magnetic flux. Using right hand thumb rule, we can say that excess positive charge will arrive on plate b.

(i) Galvanometer pointer moves to one side showing that a momentary current is induced in the coil A. 

(ii) Galvanometer pointer moves to the other side showing that the direction of momentarily induced current has been reversed. The phenomenon taking place here is electromagnetic induction. When the current is passed through coil B or is stopped, the magnetic field linked with coil A changes due to which an induced current is produced in the coil.

Mercury is used in making thermometers because it has wide and useful temperature range and has a uniform rate of expansion.  

This happens when the refractive index of the lens becomes equal to that of the liquid.

1. a. TRUE

2. b. Path of light undergoes deviation

3. b. At the point on the surface where the media get separated.

4. a. The difference in speed of light rays in different media.

5. b. NO

1. a. TRUE

2. b. Due to refraction

3. a. YES

4. b. When light travels from water to air it deviates.

5. c. Pencil appears to be bent more.

No, it will not change.

a) C₂ H₁₂ O₂ + 6O₂ → 6CO₂ + 6H₂ O + energy

b) 6CO₂ + 6 H₂O \(\overset{Light}\longrightarrow\) C₆H₁₂O₆ + 6O₂

Initially, both A and B are moving with the same velocity in the same direction,

∴ The initial relative velocity .

u_AB = u_A – u_B = 0

when t = 50 s,

relative acceleration = a_AB = 1 ms^-2

If s is the distance moved, then

From s = ut + 1/2at²

S = u_AB × t + 1/2 a_ABt²

S = 0 × t + 1/2 × 1 × 50²

= 2500/2 = 1250 m.

Hence, the Initial distance of separation is 1250m.

This is because the relative velocity of the train in which the person is sitting with respect to the other train is zero.

For example,

The velocity of 'A' train = 50 km/hr. due East and the velocity of 'B' train = 50 km/hr. due East.

Relative velocity of A train w.r.t., B train = 50 - 50 = 0.

And similarly Relative velocity of B w.r.t., A = 0.

The people, in their childhood, when they didn’t know the falsehood and hypocrisies of the world, when they were not corrupted by the ways of the world, shook hands with their hearts.

1. (c) ✓

2. (b) ✓

3. (d) ✓

4. (a) ✓

The tone of the poem is roughly equivalent to the mood it creates in the reader. In Once Upon a Time’ the tone of the poem in the earlier stanzas is abashed, regretful but in the last stanza the poet ends the poem in an optimistic and hopeful tone. Thus the poet begins the poem in a negative tone i.e. somber but ends positively i.e. optimism.