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Question 861
StructuredStandard5 marks
CBSE Class 11 Mathematics · Sequences and Series · Geometric progressions

In a geometric progression the fourth term equals the square of the second term, and the first term is −3. Find the seventh term.

Question 862
StructuredStandard4 marks
CBSE Class 11 Mathematics · Permutations and Combinations · Permutations

Determine r in each equation: (i) {}^5P_r=2\,{}^6P_{r-1}(ii) {}^5P_r={}^6P_{r-1}.

Question 863
StructuredStandard4 marks
CBSE Class 11 Mathematics · Linear Inequalities · One-variable inequalities

Complete every requested part of exercise 5.1, question 18: 5x – 3 > 3x – 5 x (5 x – 2) (7 x – 3)

Question 864
StructuredStandard4 marks
CBSE Class 11 Mathematics · Complex Numbers and Quadratic Equations · Conjugate and modulus

Given x−iy=(a−ib)/(c−id), prove that x²+y²=(a²+b²)/(c²+d²).

Question 865
StructuredStandard4 marks
CBSE Class 11 Mathematics · Trigonometric Functions · Trigonometric functions

Complete every requested part of exercise 3.2, question 11: tan ( x – y) = 1 + tan x tan y If we replace y by – y in Identity 10, we get tan (x – y) = tan [x + (– y)] tan x + tan (− y ) tan x − tan y = = 1 − tan x tan ( − y ) 1+ tan x tan y

Question 866
StructuredStandard2 marks
CBSE Class 11 Mathematics · Relations and Functions · Relations

If \(A=\{x,y,z\}\), \(B=\{1,2\}\), how many relations are possible from \(A\) to \(B\)?

Question 867
StructuredStandard4 marks
CBSE Class 11 Chemistry · Hydrocarbons · Conversions, directing effects and applications

Arrange benzene, n-hexane and ethyne in decreasing order of acidic behaviour. Also give reason for this behaviour.

Question 868
StructuredStandard4 marks
CBSE Class 11 Chemistry · Organic Chemistry: Some Basic Principles and Techniques · Purification and qualitative analysis

State the principles of crystallisation, distillation and chromatography, giving one example of each.

Question 869
StructuredStandard8 marks
CBSE Class 11 Chemistry · Redox Reactions · Balancing redox equations

Balance the four stated redox equations by the ion-electron method in the specified acidic or basic medium.

Question 870
StructuredStandard6 marks
CBSE Class 11 Chemistry · Equilibrium · Equilibrium constants and reaction quotient

Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as: CH3COOH (l) + C2H5OH (l) CH3COOC2H5 (l) + H2O (l) (i) Give the concentration ratio (reaction quotient), Qc, for this reaction (note: water is not in excess and is not a solvent in this reaction) (ii) At 293 K, if one starts with 1.00 mol of acetic acid and 0.18 mol of ethanol, there is 0.171 mol of ethyl acetate in the final equilibrium mixture. Determine the equilibrium constant. (iii) Starting with 0.5 mol of ethanol and 1.0 mol of acetic acid and maintaining it at 293 K, 0.214 mol of ethyl acetate is found after sometime. Has equilibrium been reached?