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On a railway route there are 15 stations...

On a railway route there are 15 stations. The number of tickets required in order that it may be possible to book a passenger from every station to every other is

A

105

B

210

C

`15!`

D

`15!//2!`

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The correct Answer is:
B
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An orbital is designated by certain values of first three quantum numbers (n, l and m) and according to Pauli.s exclusion principle, no two electrons in a atom can have all the for quantum numbers equal. N, l and m denote size, shape and orientation of the orbital. The permissible values of n are 1,2,3.... prop while that of 1 are all possible integral values from 0 to n-n. Orbitals with same values of n and 1 but different values of m (where m can have any integral values from 1 to +1 including zero) are of equal energy and are called degenerate orbitals. However degeneracy is destroyed in homogeneous external magnetic field due to different extent of interaction between the applied field and internal electronic magnet of different orbitals differing in orientations. In octahedral magnetic field external magnetic field as oriented along axes while in tetrahedral field the applied field actas more in between the axes than that on the axes themselves. For 1=0, 1,2,3,...., the states (called sub-shells) are denoted by the symbol s,p,d,f.....respectively. After f, the subshells are denoted by letters alphabetically 1 determines orbital angular motion (L) of electron as L = sqrt(l(l+1))(h)/(2pi) ON the other hand, m determines Z-component of orbital angular momentum as L_(Z) = m((h)/(2pi)) Hund.s rule states that in degenerate orbitals electrons do not pair up unless and until each each orbitals has got an electron with parallesl spins Besides orbital motion,an electron also posses spin-motion. Spin may be clockwise and anticloskwise. Both these spin motions are called two spins states of electrons characterized by spin Q.N (s) : s = +(1)/(2) and = -(1)/(2) respectively The sum of spin Q.N. of all the electrons is called total spin(s) and 2s+1 is called spin multiplicity of the configuration as a whole. The spin angular momentum of an electron is written as L_(s) = sqrt(s(s+1))(h)/(2pi) The orbital angular momentum of electron (l=1) makes an angles of 45^(@) from Z-axis. The L_(z) of electron will be

An orbital is designated by certain values of first three quantum numbers (n, l and m) and according to Pauli.s exclusion principle, no two electrons in a atom can have all the for quantum numbers equal. N, l and m denote size, shape and orientation of the orbital. The permissible values of n are 1,2,3.... prop while that of 1 are all possible integral values from 0 to n-n. Orbitals with same values of n and 1 but different values of m (where m can have any integral values from 1 to +1 including zero) are of equal energy and are called degenerate orbitals. However degeneracy is destroyed in homogeneous external magnetic field due to different extent of interaction between the applied field and internal electronic magnet of different orbitals differing in orientations. In octahedral magnetic field external magnetic field as oriented along axes while in tetrahedral field the applied field actas more in between the axes than that on the axes themselves. For 1=0, 1,2,3,...., the states (called sub-shells) are denoted by the symbol s,p,d,f.....respectively. After f, the subshells are denoted by letters alphabetically 1 determines orbital angular motion (L) of electron as L = sqrt(l(l+1))(h)/(2pi) ON the other hand, m determines Z-component of orbital angular momentum as L_(Z) = m((h)/(2pi)) Hund.s rule states that in degenerate orbitals electrons do not pair up unless and until each each orbitals has got an electron with parallesl spins Besides orbital motion,an electron also posses spin-motion. Spin may be clockwise and anticloskwise. Both these spin motions are called two spins states of electrons characterized by spin Q.N (s) : s = +(1)/(2) and = -(1)/(2) respectively The sum of spin Q.N. of all the electrons is called total spin(s) and 2s+1 is called spin multiplicity of the configuration as a whole. The spin angular momentum of an electron is written as L_(s) = sqrt(s(s+1))(h)/(2pi) According to Hund.s rule, the distribution of electron within the various orbitals of a given sub-shell is one which is associated with

Outcomes of which of the following experiments are equally likely ?(1)Getting a digit 1, 2, 3, 4, 5 or 6 when a dice is rolled.(2)Selecting a different colour ball from a bag of 5 red balls, 4 blue balls and 1 blackball.Winning in a game of carrom.(3) Units place of a two digit number selected may be 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9.(4) Selecting a different colour ball from a bag of 10 red balls, 10 blue balls and 10 black balls.(5) Raining on a particular day of July.Are the outcomes of every experiment equally likely?

AAKASH SERIES-PERMUTATIONS & COMBINATIONS-EXERCISE-II
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  2. If ""^(56)P((r+6)):""^(54)P((r+3))=30800:1, find r.

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  3. On a railway route there are 15 stations. The number of tickets requir...

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  4. The number of ways of 3 scholarships of unequal value be awarded to 17...

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  5. On a new year day every student of a class sends a card to every other...

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  6. The number of other permutations of the letters of the word SIMPLETON ...

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  7. The letters of the word "ARTICLE” are taken four at a time and arrange...

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  8. The number of arrangements that can be formed out of GANESHPURI so tha...

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  9. The number of arrangements that can be formed out of GANESHPURI so tha...

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  10. The number of arrangements that can be formed out of GANESHPURI so tha...

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  11. The number of arrangements that can be formed with the letters of the ...

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  12. The letters of the word “HOSTEL' are arranged so that vowels occupy th...

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  13. The letters of the word “RANDOM' are arranged in all possible ways. Th...

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  14. The number of ways of arranging 6 players to throw the cricket b...

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  15. The number of ways in which 5 boys and 5 girls can be arranged in a ro...

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  16. The number of ways in which 5 boys and 5 girls can be arranged in a ro...

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  17. A : the number of ways in which 5 boys and 5 girls can sit in a r...

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  18. The number of ways in which ten candidates A(1),A(2),A(3),A(4),……,A(10...

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  19. The number of ways in which ten candidates A(1),A(2),A(3),A(4),……,A(10...

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  20. The number of ways in which candidates A1,A2 ,. . . A(10) can b...

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