Q63.If the number of 5-element subsets of the set A = {a1, a2, โฆ , a20} of 20 distinct elements is k times the number of 5-element subsets containing a4 , then k is (1) 5 (2) 20 7 (3) 4 (4) 10 3
What This Question Tests
The problem requires calculating the number of 5-element subsets from 20 elements, and then the number of 5-element subsets that must include a specific element, using the combination formula.
Concepts Tested
Formulas Used
nCr = n! / (r! * (n-r)!)
๐ NCERT Sections This Tests
5.23 โ Give The Oxidation State, D Orbital Occupation And Coordination Number Of
Chemistry Class 11 ยท Chapter 5
5.23 Give the oxidation state, d orbital occupation and coordination number of the central metal ion in the following complexes: (i) K3[Co(C2O4)3] (iii) (NH4)2[CoF4] (ii) cis-[CrCl2(en)2]Cl (iv) [Mn(H2O)6]SO4
3.23 โ The Rate Constant For The Decomposition Of Hydrocarbons Is 2.418 ร 10โ5Sโ1
Chemistry Class 11 ยท Chapter 3
3.23 The rate constant for the decomposition of hydrocarbons is 2.418 ร 10โ5sโ1 at 546 K. If the energy of activation is 179.9 kJ/mol, what will be the value of pre-exponential factor.
5.28 โ How Many Ions Are Produced From The Complex Co(Nh3)6Cl2 In Solution?
Chemistry Class 11 ยท Chapter 5
5.28 How many ions are produced from the complex Co(NH3)6Cl2 in solution? (i) 6 (ii) 4 (iii) 3 (iv) 2 139 Coordination Compounds Reprint 2025-26
๐ Question Details
- Chapter
- Permutation & Combination
- Topic
- Combinations
- Year
- 2012
- Shift
- 07 May Online
- Q Number
- Q63
- Type
- MCQ
- NCERT Ref
- Class 11 Mathematics Ch 7: Permutations and Combinations
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