Tags Class 12th

Class 12th

Get insights from 11.9k questions on Class 12th, answered by students, alumni, and experts. You may also ask and answer any question you like about Class 12th

Follow Ask Question

11.9k

Questions

Discussions

Active Users

Followers

New answer posted

7 months ago

Class 12th Maths

Let y = y(x) be solution of the differential equation logₑ(dy/dx) = 3x + 4y, with y(0) = 0.
If y(-2/3 logₑ2) = α logₑ2, then the value of α is equal to:

0 Follower 7 Views

Vishal Baghel

Contributor-Level 10

A = [, [-1, 4]. |A| = 2 - 1 = 1.
Characteristic equation: λ² - tr (A)λ + |A| = 0 ⇒ λ² - 3λ + 1 = 0.
By Cayley-Hamilton, A² - 3A + I = 0. A? ¹ (A² - 3A + I) = A - 3I + A? ¹ = 0.
A? ¹ = 3I - A.
Comparing with A? ¹ = αI + βA, we get α=3, β=-1.
4 (α - β) = 4 (3 - (-1) = 16.

0 0

New answer posted

7 months ago

Class 12th Continuity and Differentiability

Let f: [-π/4, π/4] → R be defined as
f(x) = { (1 + |sin x|)³ᵃ/|sin x|, -π/4 < x < 0; b, x = 0; e^(cot 4x / cot 2x), 0 < x < /4 }
If f is continuous at x = 0, then the value of 6a + b² is equal to:

0 Follower 38 Views

Vishal Baghel

Contributor-Level 10

L.H.L = lim (x→0? ) (1 + |sin x|)³? /|sin x| = lim (h→0) (1 + sinh)³? /sinh = e³?
R.H.L = lim (x→0? ) e^ (cot 4x / cot 2x) = lim (x→0? ) e^ (tan 2x / tan 4x) = e¹/².
f (0) = b.
For continuity, e³? = e¹/² = b.
3a = 1/2 ⇒ a = 1/6. b = e¹/².
6a + b² = 6 (1/6) + (e¹/²)² = 1 + e

0 0

New answer posted

7 months ago

Class 12th Chemistry

Consider the cell at 25°C
Zn | Zn²?(aq), (1M) Fe³?(aq), Fe²?(aq) | Pt(s)
The fraction of total iron present as Fe³? ion at the cell potential of 1.500V is x * 10?². The value of x is ______ (Nearest integer).
(Given: E?(Fe³?/Fe²?) = 0.77V, E?(Zn²?/Zn) = -0.76V)

0 Follower 9 Views

Raj Pandey

Contributor-Level 9

Fe? ³ + e? → Fe? ² E° = 0.77V
Zn (s) → Zn? ² + 2e? ; E° = 0.76V
Cell reaction: 2Fe? ³ + Zn → 2Fe? ² + Zn? ² E°cell = 1.53V
Ecell = E°cell - (0.059/2)log ( [Zn? ²] [Fe? ²]²/ [Fe? ³]²)
1.5 = 1.53 - (0.06/2)log (1 * [Fe? ²]²/ [Fe? ³]²)
-0.03 = -0.03 log ( [Fe? ²]/ [Fe? ³])²
1 = log ( [Fe? ²]/ [Fe? ³])² => [Fe? ²]/ [Fe? ³] = 10
Let total iron = T. [Fe? ³] + [Fe? ²] = T. [Fe? ³] + 10 [Fe? ³] = T. 11 [Fe? ³] = T.
fraction of Fe? ³ = [Fe? ³]/T = 1/11 ≈ 0.09
This solution seems to differ from the image. Let's follow the image's steps.
log ( [Fe? ²]/ [Fe? ³])² = 1 => ( [Fe? ²]/ [Fe? ³])² = 10
[Fe? ²]/ [Fe?

...more

0 0

New answer posted

7 months ago

Class 12th Maths

Let the plane passing through the point (-1, 0, -2) and perpendicular to each of the planes 2x + y - z = 2 and x - y - z = 3 be ax + by + cz + 8 = 0. Then the value of a + b + c is equal to:

0 Follower 6 Views

Vishal Baghel

Contributor-Level 10

Normal to the required plane is perpendicular to the normals of the given planes.
n = n? * n? = (2i + j - k) * (i - j - k) = -2i + j - 3k.
Equation of the plane is -2 (x+1) + 1 (y-0) - 3 (z+2) = 0
-2x - 2 + y - 3z - 6 = 0
-2x + y - 3z - 8 = 0
2x - y + 3z + 8 = 0
Comparing with ax + by + cz + 8 = 0, we get a=2, b=-1, c=3.
a+b+c = 2-1+3 = 4.

0 0

New answer posted

7 months ago

Class 12th Ncert Solutions Chemistry Class 12th

When 10 ml of an aqueous solution of Fe²? ions was titrated in the presence of dil H?SO? using diphenylamine indicator, 15 mL of 0.02 M solution of K?Cr?O? was required to get the end point. The molarity of the solution containing Fe²? ions is x * 10?²M. The value of x is ______. (Nearest integer)

0 Follower 3 Views

Raj Pandey

Contributor-Level 9

Cr? O? ²? + 6Fe²? + 14H? → 2Cr³? + 6Fe³? + 7H? O
n-factor for Cr? O? ²? = 6, for Fe²? = 1
M.E Cr? O? ²? = M.E Fe²?
M? V? n? = M? V? n?
0.02 * 15 * 6 = M? * 10 * 1
M? = (0.02 * 15 * 6)/10 = 0.18 M = 18 * 10? ² M

0 0

New answer posted

7 months ago

Class 12th Maths

If |a| = 2, |b| = 5 and |a * b| = 8, then a . b is equal to:

0 Follower 8 Views

alok kumar singh

Contributor-Level 10

|a * b|² + |a . b|² = |a|²|b|²
8² + (a . b)² = 2² * 5²
64 + (a . b)² = 100
(a . b)² = 36
a . b = 6 (since angle seems acute from options, but could be -6).

0 0

New answer posted

7 months ago

Class 12th Maths

Let a = i + j + 2k and b = -i + 2j + 3k. Then the vector product (a + b) * ((a * ((a - b) * b)) * b) is equal to:

0 Follower 24 Views

Vishal Baghel

Contributor-Level 10

a = i + j + 2k
b = -i + 2j + 3k
a + b = 3j + 5k
a . b = -1 + 2 + 6 = 7
a * b = |i, j, k; 1, 2; -1, 2, 3| = -i - 5j + 3k
(a - b) * b) = (a * b) - (b * b) = a * b
(a * (a - b) * b) = a * (a * b) = (a . b)a - (a . a)b = 7a - 6b
. The expression becomes (a + b) * (7a - 6b) * b)
= (a + b) * (7 (a * b)
= 7 [ (a * (a * b) + (b * (a * b) ]
= 7 [ (

...more

0 0

New answer posted

7 months ago

Class 12th Chemistry Solutions

CO? gas is bubbled through water during a soft drink manufacturing process at 298 K. If CO? exerts a partial pressure of 0.835 bar then x m mol of CO? would dissolve in 0.9 L of water. The value of x is ______ (Nearest integer). (Henry's law constant for CO? at 298 K is 1.67*10³ bar)

0 Follower 3 Views

Raj Pandey

Contributor-Level 9

P (CO? ) = K? X (CO? )
X (CO? ) = P (CO? )/K? = 0.835 / (1.67 * 10³) = 0.5 * 10? ³
X (CO? ) = n (CO? )/ (n (CO? ) + n (H? O) ≈ n (CO? )/n (H? O) (since n (CO? ) << n (H? O)
n (H? O) in 0.9L = 900g/18gmol? ¹ = 50 mol
n (CO? ) = X (CO? ) * n (H? O) = 0.5 * 10? ³ * 50 = 25 * 10? ³ moles = 25 mmol

0 0

New answer posted

7 months ago

Class 12th Chemistry

Which one of the products of the following reactions does not react with Hingberg reagent to form sulphonamide?
[Four different reduction reactions of nitriles and nitro compounds]