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

11 months ago

Class 12th Maths

The sum of the maximum and minimum values of the function f(x) = $| 5 x - 7 | + [x^{2} + 2 x]$ in the interval $[\frac{5}{4}, 2],$ where [t] is the greatest integer $\leq t$ is

0 Follower 35 Views

Payal Gupta

Contributor-Level 10

$f (x) = | 5 x - 7 | + [x^{2} + 2 x]$

$= | 5 x - 7 | + [{(x + 1)}^{2}] - 1$

f $(\frac{7}{4}) = 0 + 4 = 4$

as both |5x – 7| and x² + 2x are increasing in nature after x = 7/5

f (2) = 3 + 8 = 11

$f {(\frac{7}{5})}_{m i n} - 4 a n d f {(2)}_{m a x} = 11$

Sum is 4 + 11 = 15

0 0

New answer posted

11 months ago

Class 12th Maths Matrices

Let A = $| \begin{matrix} 1 & a & a \\ 0 & 1 & b \\ 0 & 0 & 1 \end{matrix} |$ , a, b $\in$ R. If for some n $\in$ N, Aⁿ = $| \begin{matrix} 1 & 48 & 2160 \\ 0 & 1 & 96 \\ 0 & 0 & 1 \end{matrix} |$ then n + a + b is equal to

0 Follower 45 Views

Payal Gupta

Contributor-Level 10

$A = [\begin{matrix} 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{matrix}] + [\begin{matrix} 0 & a & a \\ 0 & 0 & b \\ 0 & 0 & 0 \end{matrix}] = l + B$

$B^{2} = [\begin{matrix} 0 & a & a \\ 0 & 0 & b \\ 0 & 0 & 0 \end{matrix}] * [\begin{matrix} 0 & a & a \\ 0 & 0 & b \\ 0 & 0 & 0 \end{matrix}] = [\begin{matrix} 0 & 0 & a b \\ 0 & 0 & 0 \\ 0 & 0 & 0 \end{matrix}]$

B³ = 0

$∴ A^{n} = {(1 + B)}^{n} =^{n} C_{0} l +^{n} C_{1} B +^{n} C_{2} B^{2} +^{n} C_{3} B^{3} + . . . .$

On comparing we get na = 48, nb = 96 and na + $\frac{n (n - 1)}{2} a b = 2160$

$\Rightarrow a = 4, n = 12 a n d b = 8$

$\Rightarrow n + a + b = 24$

0 0

New answer posted

11 months ago

Class 12th Maths

Let f(x) be a quadratic polynomial with leading coefficient 1 such that f(0) = p, p $\neq 0$ , and f(1) = $\frac{1}{3} .$ If the equations f(x) = 0 and fo fo fo f(x) = 0 have a common real root , then f(3) is equal to

0 Follower 23 Views

Payal Gupta

Contributor-Level 10

Let f (x) = (x -α) (x - β)

It is given that f (0) = p = p

and

$f (1) = \frac{1}{3} \Rightarrow (1 - α) (1 - β) = \frac{1}{3}$

Now, let us assume that is the common root of f (x) = 0 and fofofof (x) = 0

fofofof (x) = 0

$f (- 3) = (- 3 - \frac{7}{6}) (3 - 3) = 25$

0 0

New answer posted

11 months ago

Class 12th Chemistry

The total number of monobromo derivatives formed by the alkanes with molecular formula C₅H₁₂ is (excluding stereo isomers)___________.

0 Follower 5 Views

Payal Gupta

Contributor-Level 10

Consider the image below

0 0

New answer posted

11 months ago

Class 12th Chemistry

The separation of two coloured substances was done by paper chromatography. The distance travelled by solvent front, substance A and substance B from the base line are 3.25cm, 2.08cmand 1.05cm, respectively. The ratio of R_f values of A to B is ________.

0 Follower 4 Views

Payal Gupta

Contributor-Level 10

$R_{f}^{0} = distance travelled by the solute$ $/$ $/ distance travelled by the solvent$

${(R_{f})}_{A} = \frac{2.08}{3.25} {(R_{f})}_{B} = \frac{1.05}{3.25}$

$\frac{{(R_{f})}_{A}}{{(R_{f})}_{B}} = \frac{2}{1}$

0 0

New answer posted

11 months ago

Class 12th Chemistry

A sample of 4.5mg of an unknown monohydric alcohol, R-OH was added to methylmagnesium iodide. A gas is evolved and is collected and its volume measured to be 3.1 mL. The molecular weight of the unknown alcohol is ____________ g/mol.

[Nearest integer]

0 Follower 3 Views

Payal Gupta

Contributor-Level 10

(Calculation is done considering STP condition)

$R O H + C H_{3} M g l \to C H_{4} + R O M g l$

No. of moles ROH = no. of moles of CH4

$\frac{4.5 * 1 0^{- 3}}{M} = \frac{31}{22400} \Rightarrow 32.52 \approx 33 g m / m o l e$

0 0

New answer posted

11 months ago

Class 12th Chemistry

The spin-only magnetic moment value of M³+ ion (in gaseous state) from the pairs Cr³⁺/Cr²⁺, Mn³⁺/Mn²⁺, Fe³⁺/Fe²⁺ and Co³⁺/Co²⁺ that has negative standard electrode potential, is________ B.M [Nearest integer]

0 Follower 19 Views

Payal Gupta

Contributor-Level 10

In given electrodes, only $E_{C r^{3 +} / C r^{2 +}}^{0}$ is negative

Cr (24) – [Ar] 4s¹3d⁵4p⁰

Number of unpaired electrons = 3

$μ = \sqrt[]{n (n + 2)} B M = \sqrt[]{3 (3 + 2)} B M = 3.97 B M \approx θ 4 B M$

0 0

New answer posted

11 months ago

Class 12th Chemistry

The sum of number of lone pairs of electrons present on the central atoms of XeO₃, XeOF₄ and XeF₆, is___________.

0 Follower 7 Views

Payal Gupta

Contributor-Level 10

XeO₃ ⇒ Number of lone pair = 1

XeOF₄ ⇒ Number of lone pair = 1

XeF₆ ⇒ Number of lone pair = 1

0 0

New answer posted

11 months ago

Class 12th Chemistry Chemical Kinetics

For the decomposition of azomethane,

CH₃N₂CH₃(g) → CH₃CH₃(g) + N₂(g), a first order reaction, the variation in partial pressure with time at 600 K is given as.

0 Follower 3 Views

Payal Gupta

Contributor-Level 10

For first order reaction,

$l n (\frac{P}{P_{0}}) = - k . t$

$K = 3.465 * 1 0^{4}$

$t_{1 / 2} = \frac{0.693}{3.465 * 1 0^{4}} = 2 * 1 0^{- 5}$ sec

0 0

New answer posted

11 months ago

Class 12th Chemistry

When the excited electron of a H atom from n = 5 drops to the ground state, the maximum number of emission lines observed are____________.

0 Follower 1 View

Payal Gupta

Contributor-Level 10

For single H- atom, maximum number of spectral lines = (n – 1), n = orbit number of excited electron.

0 0

Get authentic answers from experts, students and alumni that you won't find anywhere else

On Shiksha, get access to

66k Colleges
1.2k Exams
703k Reviews
1850k Answers

Community GuidelinesUser Points System

QuestionsDiscussionsTags

Need guidance on career and education? Ask our experts

Your Question

Class 12th

Questions

Discussions

Active Users

Followers

All

Discussions

Unanswered Questions

Share Your College Life Experience