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Question 61

West Bengal Group D 2017• Full Test

If \(\frac{a}{{1 - a}} + \frac{b}{{1 - b}} + \frac{c}{{1 - c}} = 1\). then the value of \(\frac{1}{{1 - a}} + \frac{1}{{1 - b}} + \frac{1}{{1 - c}} \) is

  1. AOption (a)

    0

  2. BOption (b)

    1

  3. COption (c)

    2

  4. DOption (d)

    4

View answer & explanation

Correct answer

Answer: (d)D.

4

Why this answer is correct

Given:

(a/1 – a) + (b/1 – b) + (c/1 – c) = 1

Calculation:

Add 1 to 1st term on LHS, add 1 to second term and again 1 to last term. Balance this by adding 3 to RHS.

[1 + a/(1 – a)] + [1 + b/(1 – b)] + [1 + c/ (1 – c)] = 1 + 3

⇒ (a + 1 – a)/(1 – a) + (b + 1 – b)/(1 – b) + (c + 1 – c)/(1 – c) = 1 + 3

⇒ 1/(1 – a) +  (1/1 – b) + (1/ 1 – c) = 4

∴ The value of (1/1 – a) + (1/1 – b) + (1/ 1 – c) is 4.

Question 62

West Bengal Group D 2017• Full Test

The dance-drama 'Chitrangada' was composed by

  1. AOption (a)

    Girish Chandra Ghosh

  2. BOption (b)

    Michael Madhusudhan Dutt

  3. COption (c)

    Rabindranath Tagore

  4. DOption (d)

    Utpal Dutta

View answer & explanation

Correct answer

Answer: (c)C.

Rabindranath Tagore

Why this answer is correct

The correct answer is Rabindranath Tagore.

Chitrangada is a dance-drama by Rabindranath Tagore published in 1892, based on the story of Chitrāngadā, the mythological princess of the Kingdom of Manipur and one of the wives of Arjuna according to the Mahabharata.

PlaywrightDramas
Girish Chandra GhoshBuddhadev Charit, Ashoka, Shankaracharya, Prahlad Charit
Michael Madhusudhan DuttSarmishta, Padmavati, Ekei Ki Boley Sabyata, Krishna Kumari, Buro Shaliker Ghare Ron
Rabindranath TagoreChitrangada, Chandalika, Dak Ghar, Shyama
Utpal DuttaAngar, Kallol

Question 63

West Bengal Group D 2017• Full Test

If \((a^2 + b^2)^3 = (a^3 + b^3)^2\), then the value of \(\frac{a}{b} + \frac{b}{a}\) is

  1. AOption (a)

    1

  2. BOption (b)

    \(\frac{2}{3}\)

  3. COption (c)

    \(\frac{3}{2}\)

  4. DOption (d)

    6

View answer & explanation

Correct answer

Answer: (b)B.

\(\frac{2}{3}\)

Why this answer is correct

Given:

(a² + b²)³ = (a³ + b³)²

Formula Used:

(a + b)3 = a3 + b3 + 3a2b + 3ab2

(a + b)2 = a2 + b2 + 2ab

Calculation:

a6 + b6 + 3a4 b2 + 3a2b4 = a6 + b6 +2a3b3

Eliminating a6 + b6 from both sides:

3a²b²(a² +b²) = 2a3b3

⇒ 3a²b²(a² +b²) = 2ab(a²b²)

⇒ 3(a² +b²) = 2ab

⇒ a²/ab + b²/ab = 2/3

⇒ a/b + b/a = 2/3

∴ Required value is 2/3

Question 64

West Bengal Group D 2017• Full Test

Kinetic friction in comparison to static friction is

  1. AOption (a)

    more

  2. BOption (b)

    less

  3. COption (c)

    equal

  4. DOption (d)

    equal or more

View answer & explanation

Correct answer

Answer: (b)B.

less

Why this answer is correct

The correct answer is Less.

  • Static and sliding friction
  • The impending motion of the body is opposed by static friction.
  • When the external force exceeds the maximum limit of static friction, the body begins to move.
  • Kinetic friction
  • Once the body is in motion, it is subject to sliding or kinetic friction which opposes relative motion between the two surfaces in contact.
  • Kinetic friction is usually less than the maximum value of static friction.

Question 65

West Bengal Group D 2017• Full Test

The famous political book. 'The Prince' was written by

  1. AOption (a)

    Dante

  2. BOption (b)

    Machiavelli

  3. COption (c)

    Boccaccio

  4. DOption (d)

    Petrarch

View answer & explanation

Correct answer

Answer: (b)B.

Machiavelli

Why this answer is correct

The correct answer is option 2 i.e. Machiavelli.

AuthorMajor Works
DanteDivine Comedy, The New Life, The Banquet
MachiavelliThe Prince, Discourses on Livy
BoccaccioThe Decameron, On Famous Women
PetrarchFragments of Vernacular Matters, Triumphs, Remedies for Fortune Fair and Foul, Petrarch's Guide to the Holy Land

Question 66

West Bengal Group D 2017• Full Test

Which region in the world is famous for producing citrus fruit?

  1. AOption (a)

    Mediterranean Region

  2. BOption (b)

    Monsoon Region

  3. COption (c)

    Equatorial Region

  4. DOption (d)

    Temperate Region

View answer & explanation

Correct answer

Answer: (a)A.

Mediterranean Region

Why this answer is correct

The correct answer is option 1 i.e. the Mediterranean Region.

Key Points

  • Most of the east and northeast margins of the continents are covered by temperate evergreen and deciduous trees.
  • The west and south-west margins of the continents are different. They have Mediterranean vegetation.
  • It is mostly found in the areas around the Mediterranean sea in Europe, Africa and Asia, hence the name.
  • This kind of vegetation is also found outside the actual Mediterranean region in California in the USA, south-west Africa, southwestern South America and Southwest Australia.
  • These regions are marked for hot dry summers and mild rainy winters.
  • Citrus fruits such as oranges, figs, olives and grapes are commonly cultivated here because people have removed the natural vegetation in order to cultivate what they want to.
  • Mediterranean trees adapt themselves to dry summers with the help of their thick barks and wax-coated leaves which help them reduce transpiration.
  • Mediterranean regions are known as ‘Orchards of the world’ for their fruit cultivation.
  • There isn’t much wildlife here.

Question 67

West Bengal Group D 2017• Full Test

In the battle field, the technique of 'Rumi' was used by

  1. AOption (a)

    Babar

  2. BOption (b)

    Akbar

  3. COption (c)

    Sher Shah

  4. DOption (d)

    Aurangazeb

View answer & explanation

Correct answer

Answer: (a)A.

Babar

Why this answer is correct

The correct answer is option 1 i.e. Babar.

  • Babur successfully applied the Rumi (Ottoman) method of warfare in The First Battle of Panipat in 1526.
  • As the Afghans advanced to attack the right flank; Babur ordered his reserve forces to move.
  • The Afghans, greater in number, were unable to move forward nor backward. They were attacked from both sides.
  • This created total confusion among the Afghan forces, Babur took full advantage of the situation and his right and left wings soon attacked the Afghan forces from the rear side.
  • This was followed with the opening up of fireshots and this completely paralysed the Afghan army.
  • Afghan casualties reported by Babur were approximately 20,000 including the Sultan Ibrahim Lodi.
  • In the battle it was not Babur's artillery but his 'superb tactics' and the 'mounted archers' played the decisive role, a fact which Babur himself acknowledged.

Question 68

West Bengal Group D 2017• Full Test

The points A(1, 0), B(5, 0) and C(3,3) are

  1. AOption (a)

    vertices of an isosceles triangle

  2. BOption (b)

    vertices of an equilateral triangle

  3. COption (c)

    vertices of a right angled triangle

  4. DOption (d)

    vertices of a scalene triangle

View answer & explanation

Correct answer

Answer: (a)A.

vertices of an isosceles triangle

Why this answer is correct

Concept:

In an Isosceles triangle, Any two sides are always equal:

Distance formula: AB2 = (x2 - x1)2 + (y2 - y1)2

Calculation:

Points are A(1, 0), B(5, 0) and C(3,3) 

AB2 = (5 - 1)2 + (0 - 0)2 = 16 unit

BC2 = (3 - 5)2 + (3 - 0)2 = 13 unit

AC2 = (3 - 1)2 + (3 - 0)2 = 13 unit

∴ 2 sides, AC and BC are equal and hence points are vertices of an isosceles triangle

Question 69

West Bengal Group D 2017• Full Test

The H.C.F. of .9, .09 and .009 is

  1. AOption (a)

    .009

  2. BOption (b)

    .9

  3. COption (c)

    .09

  4. DOption (d)

    9

View answer & explanation

Correct answer

Answer: (a)A.

.009

Why this answer is correct

Concept:

H.C.F. = H.C.F.(of numerator)/L.C.M.(of denominator)

Calculation:

Convert decimals into fractions:

9/10 , 9/100 , 9/1000

H.C.F. = H.C.F.(9, 9, 9)/L.C.M.(10, 100, 1000)

⇒ H.C.F. = 9/1000 = 0.009

Question 70

West Bengal Group D 2017• Full Test

'Oil of vitroil' is

  1. AOption (a)

    HCI

  2. BOption (b)

    HNO3

  3. COption (c)

    HCOOH

  4. DOption (d)

    H2SO4

View answer & explanation

Correct answer

Answer: (d)D.

H2SO4

Why this answer is correct

The correct answer is option 4 i.e. H2SO4.

A vitriol (from the Latin word vitriolum, meaning "glassy") is a compound containing a sulphate as the crystals of several metallic sulphates resemble pieces of coloured glass.

Chemical Formula & NameCommon Name
HCl, Hydrochloric AcidSalt Acid
HNO3, Nitric AcidAqua fortis (Latin for "strong water") and Spirit of Niter,
HCOOH, Methanoic AcidFormic Acid
H2SO4, Sulphuric AcidOil of Vitriol