Tags Class 12th

Class 12th

Get insights from 12k 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

12k

Questions

Discussions

Active Users

Followers

New answer posted

2 months ago

Class 12th Solutions

The number of chlorine atoms in 20 mL of chlorine gas at STP is ______10²¹ (Round off to the nearest integer).
[Assume chlorine is an ideal gas at STP, R = 0.083 L bar mol⁻¹ K⁻¹, NA = 6.023 *10²³]

0 Follower 6 Views

alok kumar singh

Contributor-Level 10

Using the Ideal Gas Law, PV = nRT:

P = 1 bar

V = 20 mL = 0.020 L

R = 0.083 L·bar·mol? ¹·K? ¹

T = 273 K

n = PV / RT = (1 * 0.020) / (0.0831 * 273) = 8.8 * 10? mol of Cl?

Number of Cl? molecules (N) = n * N_A = (8.8 * 10? ) * (6.022 * 10²³) = 5.3 * 10²? molecules.

Number of Cl atoms = 2 * (5.3 * 10²? ) = 1.06 * 10²¹.

The answer, rounded off to the nearest integer for the power of 10²¹, is 1.

0 0

New answer posted

2 months ago

Class 12th Chemistry

A 1 molal K4[Fe(CN)6] solution has a degree of dissociation of 0.4. Its boiling point is equal to that of another solution which contains 18.1 weight percent of a non electrolytic solute A. The molar mass of A is ______ u. (Round off to the nearest integer).
[Density of water = 1.0 g cm?³]

0 Follower 3 Views

alok kumar singh

Contributor-Level 10

For the dissociation of K? [Fe (CN)? ]? 4K? + [Fe (CN)? ]? , the number of ions produced (n) is 5.

The degree of dissociation (α) is related to the van't Hoff factor (i) by α = (i-1)/ (n-1).

Given α = 0.4: 0.4 = (i - 1) / (5 - 1) => 1.6 = I - 1 => I = 2.6

Using the depression in freezing point formula (ΔTf = i·Kf·m), and equating the ΔTf for two different solutions:
ΔTf (K? [Fe (CN)? ]) = ΔTf (A)
i? ·Kf·m? = i? ·Kf·m?
(2.6) * [ (18.1 / M) / (100-18.1)/1000] = (1) * [ (w? /M? ) / (W? /1000)]
The problem simplifies to finding the molar mass M of solute A:
2.6 * [18.1 / (M * 81.9)] * 1000 = [w? /M? ] * [1000/W? ]
Assuming the secon

...more

0 0

New answer posted

2 months ago

Class 12th Maths

If the function f(x) = (cos(sin x) - cos x) / x⁴ is continuous at each point in its domain and f(0) = 1/k, then k is .

0 Follower 4 Views

Vishal Baghel

Contributor-Level 10

f (x) = (cos (sin x) - cos x) / x? We need lim (x→0) f (x) = 1/k.
Using cos C - cos D = -2 sin (C+D)/2) sin (C-D)/2).
f (x) = -2 sin (sin x + x)/2) sin (sin x - x)/2) / x?
For small x, sin x ≈ x.
lim (x→0) f (x) = lim -2 * ( (sin x + x)/2 ) * ( (sin x - x)/2 ) / x?
Using series expansion: sin x = x - x³/3! + x? /5! - .
sin x + x = 2x - x³/6 + .
sin x - x = -x³/6 + x? /120 - .
f (x) ≈ -2 * ( (2x)/2 ) * ( (-x³/6)/2 ) / x?
≈ -2 * (x) * (-x³/12) / x?
≈ (2x? /12) / x? = 2/12 = 1/6.
So, 1/k = 1/6 ⇒ k = 6.

0 0

New answer posted

2 months ago

Class 12th Chemistry

Consider the above reaction. The percentage yield of amide product is ______.
Benzoyl chloride (0.140 g) + Diphenylamine (0.388 g) → N,N-Diphenylbenzamide (0.210 g)
(Round off to the nearest integer).
(Given: Atomic mass: C: 12.0 u, H:1.0 u, N: 14.0 u, O: 16.0 u, Cl: 35.5 u)

0 Follower 6 Views

alok kumar singh

Contributor-Level 10

0 0

New question posted

2 months ago

Class 12th Maths

If [.] represents the greatest integer function, then the value of ∫[from 1 to 5] ([x²] - cos x) dx is.

0 Follower 6 Views

New answer posted

2 months ago

Class 12th Maths

If the equation of the plane passing through the line of intersection of the planes 2x - 7y + 4z - 3 = 0, 3x – 5y + 4z + 11 = 0 and the point (-2, 1, 3) is ax + by + cz - 7 = 0, then the value of 2a + b + c - 7 is.

0 Follower 2 Views

Vishal Baghel

Contributor-Level 10

The equation of the plane passing through the line of intersection is:
(2x - 7y + 4z - 3) + λ (3x - 5y + 4z + 11) = 0.
The plane passes through the point (-2, 1, 3).
(2 (-2) - 7 (1) + 4 (3) - 3) + λ (3 (-2) - 5 (1) + 4 (3) + 11) = 0
(-4 - 7 + 12 - 3) + λ (-6 - 5 + 12 + 11) = 0
(-2) + λ (12) = 0 ⇒ 12λ = 2 ⇒ λ = 1/6.
Substitute λ back into the equation:
(2x - 7y + 4z - 3) + (1/6) (3x - 5y + 4z + 11) = 0
Multiply by 6:
6 (2x - 7y + 4z - 3) + (3x - 5y + 4z + 11) = 0
12x - 42y + 24z - 18 + 3x - 5y + 4z + 11 = 0
15x - 47y + 28z - 7 = 0.
This is the equation ax + by + cz - 7 = 0.
So, a=15, b=-47, c=28.
We need to find the value of 2a + b

...more