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

6 months ago

Class 12th Alternating Current Overview

For a series LCR circuit, I vs curve is shown:

Choose the most appropriate answer from the options given below:

0 Follower 3 Views

alok kumar singh

Contributor-Level 10

At w_r impedance of the circuit is equal to the resistance of the circuit.

Left of w_r, circuit is mainly capacitive

Right of w_r, the circuit is mainly Inductive.

0 0

New answer posted

6 months ago

Class 12th Maths NCERT Exemplar Solutions Class 12th Chapter Six

The minimum value of the sume of the squares of the roots of x² + (3 – a)x + 1 = 2a is

0 Follower 3 Views

alok kumar singh

Contributor-Level 10

Let a and b be the roots of the equation $x^{2} + (3 - a) x + 1 = 2 a$

Therefore a + b = a – 3, ab = 1 – 2a Þ a² + b² = (a – 3)² – 2 (1 – 2a) = a² – 6a + 9 – 2 + 4a = a² – 2a + 7 = (a – 1)² + 6 Þ So, $α^{2} + β^{2} \geq 6$

0 0

New answer posted

6 months ago

Class 12th Chemistry NCERT Exemplar Solutions Class 12th Chapter One

2.4g coal is burnt in a bomb calorimeter in excess of oxygen at 298 K and 1 atm pressure. The temperature of the calorimeter rises from 298 K to 300 K. The enthalpy change during the combustion of coal is -x kJ mol^-1. The value of x is ____________.

(Given : Heat capacity of bomb calorimeter 20.0 kJ K^-1. Assume coal to be pure carbon)

0 Follower 8 Views

Vishal Baghel

Contributor-Level 10

$C (s) + O_{2} (g) \to C O_{2} (g) Δ n g = 0$

$q_{C} = 20 * 2 = 40 k J$

Number of moles of C = $\frac{2.4}{12} = 0.2 m o l e s$

$Δ H_{C} = \frac{40 k J}{0.2 m o l e} = 200 k J / m o l e$

0 0

New answer posted

6 months ago

Class 12th Chemistry NCERT Exemplar Solutions Class 12th Chapter One

The wavelength of an electron and a neutron will become equal when the velocity of the electron is x times the velocity of neutron. The value of x is ___________. (Nearest Integer)

(Mass of electron is 9.1 * 10^-31kg and mass of neutron is 1.6 * 10^-27kg)

0 Follower 2 Views

Vishal Baghel

Contributor-Level 10

Xe = Xn

MeVe = MnVn

$\frac{V e}{V n} = \frac{M n}{M e} \sim 1758.24$

0 0

New answer posted

6 months ago

Class 12th Chemistry NCERT Exemplar Solutions Class 12th Chapter One

A mixture of hydrogen and oxygen contains 40% hydrogen by mass when the pressure is 2.2 bar. The partial pressure of hydrogen is __________ bar. (Nearest Integer)

0 Follower 2 Views

Vishal Baghel

Contributor-Level 10

$x_{H_{2}} = \frac{n_{H_{2}}}{n_{H_{2}} + n_{o_{2}}} = \frac{(40 / 2)}{(40 / 2) + (60 / 32)}$ = 0.914

$P_{H_{2}} = x_{H_{2}} * P_{T} = 0.914 * 2.2 \sim 2 b a r$

0 0

New answer posted

6 months ago

Class 12th Chemistry NCERT Exemplar Solutions Class 12th Chapter One

Chlorophyll extracted form the crushed green leaves was dissolved in water to make 2 L solution of Mg of concentration 48 ppm. The number of atoms of Mg in this solution is x * 10²⁰ atoms. The value of x is _____________. (Nearest Integer)

(Given : Atomic mass of Mg is 24 g mol^-1; N_A = 6.02 * 10²³ mol^-1)

0 Follower 8 Views

Vishal Baghel

Contributor-Level 10

Mass of solute = 48 * 2 * 10^-3 gram

Atoms of Mg = 24.08 * 10²⁰

0 0

New answer posted

6 months ago

Class 12th Chemistry NCERT Exemplar Solutions Class 12th Chapter One

Given below are two statements : one is labeled as Assertion (A) and the other is labeled as

Reason (R).

Assertion (A): Experimental reaction of CH₃Cl with aniline and anhydrous AlCl₃ does not give O and P-methylaniline.

Reason (R) : The -NH₂ groups of aniline becomes deactivating because of salt formation with anhydrous AlCl₃ and hence yields m-methyl aniline as the product.

In the light of the above statements, choose the most appropriate answer from the options given below:

0 Follower 4 Views