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Q:

Species containing same number of electrons are called

A) Isotopes	B) Isobars
C) Isoelectronic	D) Isotones

Answer & Explanation Answer: C) Isoelectronic

Explanation:

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Filed Under: Chemistry

Q:

The atoms of the elements having same mass number but different atomic number are called

A) Isotopes	B) Isobars
C) Isotones	D) Isomers

Answer & Explanation Answer: B) Isobars

Explanation:

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Filed Under: Chemistry

Q:

In isotopes the number of neutrons are

A) same	B) different
C) both	D) none

Answer & Explanation Answer: B) different

Explanation:

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Filed Under: Chemistry

Q:

Wheels of diameters 7cm and 14cm start rolling simultaneously from x & y which are 1980 cm apart towards each other in opposite directions. Both of them make the same number of revolutions per second. If both of them meet after 10seconds.The speed of the smaller wheel is

A) 22m/s	B) 33m/s
C) 44m/s	D) 55m/s

Answer & Explanation Answer: A) 22m/s

Explanation:

let each wheel make x revolutions per sec. Then $[(2 π * \frac{7}{2} * x) + (2 π * 7 * x)] * 10 = 1980$ $(2 * \frac{22}{7} * \frac{7}{2} * x) + (2 * \frac{22}{7} * \frac{7}{2} * x) = 198$

$66 x = 198$

distance moved by smaller wheel in 3 revolutions

= $2 * \frac{22}{7} * \frac{7}{2} * 3 = 66 c m$

speed of smaller wheel = $\frac{66}{3}$ m/s = 22m/s

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Filed Under: Area
Exam Prep: Bank Exams
Job Role: Bank PO

Q:

A room of 5m 44cm long and 3m 74cm broad is to be paved with squre tiles. Find the least number of squre tiles required to cover the floor.

A) 136	B) 146
C) 166	D) 176

Answer & Explanation Answer: D) 176

Explanation:

area of the room = 544 x 374 sq.cm

size of largest square tile = H.C.F of 544cm and 374 cm= 34 cm

area of 1 tile = 34x34 sq cm

no. of tiles required = (544 x 374) / (34 x 34) = 176

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Filed Under: Area
Exam Prep: Bank Exams
Job Role: Bank PO

Q:

There are eight boxes of chocolates, each box containing distinct number of chocolates from 1 to 8. In how many ways four of these boxes can be given to four persons (one boxes to each) such that the first person gets more chocolates than each of the three, the second person gets more chocolates than the third as well as the fourth persons and the third person gets more chocolates than fourth person?

A) 70	B) 40
C) 72	D) 80

Answer & Explanation Answer: A) 70

Explanation:

All the boxes contain distinct number of chocolates.
For each combination of 4 out of 8 boxes, the box with the greatest number has to be given to the first person, the box with the second highest to the second person and so on.

The number of ways of giving 4 boxes to the 4 person is: 8 $C_{4}$ = 70

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Filed Under: Permutations and Combinations

Q:

When Dr. Ram arrives in his dispensary, he finds 12 patients waiting to see him. If he can see only one patients at a time,find the number of ways, he can schedule his patients if 3 leave in disgust before Dr. Ram gets around to seeing them.

A) 479001600	B) 79833600
C) 34879012	D) 67800983

Answer & Explanation Answer: B) 79833600

Explanation:

There are 12 - 3 = 9 patients.They can be seen in $12 P_{9}$ = 79833600 ways

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Filed Under: Permutations and Combinations

Q:

Compute the sum of 4 digit numbers which can be formed with the four digits 1,3,5,7, if each digit is used only once in each arrangement.

A) 105555	B) 106665
C) 106656	D) 108333

Answer & Explanation Answer: C) 106656

Explanation:

The number of arrangements of 4 different digits taken 4 at a time is given by $4 P_{4}$ = 4! = 24.All the four digits will occur equal number of times at each of the position,namely ones,tens,hundreds,thousands.

Thus,each digit will occur 24/4 = 6 times in each of the position.The sum of digits in one's position will be 6 x (1+3+5+7) = 96.Similar is the case in ten's,hundred's and thousand's places.

Therefore,the sum will be 96 + 96 x 10 + 96 x 100 + 96 x 100 = 106656

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Filed Under: Permutations and Combinations

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