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Class 12th Chemistry

The increasing order of the reactivity of the following compounds in nucleophilic addition reaction is:
(a) Di-tert-butyl ketone
(b) Acetone
(c) Acetaldehyde
(d) p-Nitrobenzaldehyde

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Raj Pandey

Contributor-Level 9

Nucleophilic addition on carbonyl compounds decreases by increasing steric hindrance.

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a year ago

Class 12th Chemistry

Consider the following molecules and statements related to them:
Molecule (P) is p-nitrophenol.
Molecule (Q) is o-nitrophenol.

(a) (Q) is more volatile than (P)
(b) (Q) has higher boiling point than (P)
(c) (P) dissolves more readily than (Q) in water
(d) pKa value of (P) is higher than (Q)

Identify the correct option from below:

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Raj Pandey

Contributor-Level 9

Due to Intramolecular hydrogen bonding, O-nitrophenol fails to spread its surface, so that its b.p is less than para-nitrophenol.

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Class 12th Maths

If value of $\frac{{(\vec{a} - \vec{b}) * (\vec{a} - \vec{b} - \vec{c})} . (\vec{a} + 2 \vec{b} - \vec{c})}{[\vec{a} \vec{b} \vec{c}]}$ is k then $\frac{k}{4}$ is

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alok kumar singh

Contributor-Level 10

$k = \frac{[\vec{a} \vec{b} \vec{c}] + 2 [\vec{a} \vec{b} \vec{c}] + [\vec{a} \vec{b} \vec{c}] - [\vec{a} \vec{b} \vec{c}]}{[\vec{a} \vec{b} \vec{c}]}$

k = 3

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a year ago

Class 12th Maths

If the area bounded by curve x + $| y |$ = 1 and the y-axis is k, then $\frac{k}{4}$ is equals to

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alok kumar singh

Contributor-Level 10

$a r e a = 2 * (\frac{1}{2} * 1 * 1) = 1 = k$

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a year ago

Class 12th Maths Continuity and Differentiability

If the function $f (x) = {\begin{matrix} 1 + s i n \frac{π x}{2} & , & x \leq 1 \\ a x + b & , & 1 < x < 3 i s c o n t i n u o u s i n \\ 6 t a n \frac{π x}{12} & , & 3 \leq x < 6 \end{matrix}$ the interval $(- \infty, 6) t h e n v a l u e o f (\frac{a - b}{8}) i s$

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alok kumar singh

Contributor-Level 10

$\underset{x \to 1^{-}}{l i m} f (x) = \underset{x \to 1^{+}}{l i m} f (x) \Rightarrow a + b = 2$

$∴ \underset{x \to 3^{-}}{l i m} f (x) = \underset{x \to 3^{+}}{l i m} f (x) \Rightarrow 3 a + b = 6 t a n \frac{3 π}{12}$

$∴$ a = 2, b = 0

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a year ago

Class 12th Vector Algebra

If $\bar{a}, \bar{b}, \bar{c}$ , such that $\bar{a} * (\bar{a} * \bar{c}) + 3 \bar{b} = 0, i f θ$ is the angle between $\bar{a} a n d \bar{c}, t h e n c o s^{2} θ$ is equal to

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alok kumar singh

Contributor-Level 10

$| \bar{a} * (\bar{a} * \bar{c}) | = | 3 \bar{b} | = 3 | \bar{b} |$

$\Rightarrow 3 = 3.2 s i n θ \Rightarrow s i n θ = \frac{1}{2} \Rightarrow c o s^{2} θ = \frac{3}{4}$

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a year ago

Class 12th Maths

If the value of $\underset{x \to 0}{L i m} {s i n^{2} (\frac{π}{2 - 3 x})}^{s e c^{2} (\frac{π}{2 - 5 x})}$ is e^-A then 'A' is

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alok kumar singh

Contributor-Level 10

$\underset{x \to 0}{l i m} {[s i n^{2} (\frac{π}{2 - 3 x})]}^{s e c^{2} (\frac{π}{2 - 5 x})}$

$e^{\underset{x \to 0}{l i m} [s i n^{2} (\frac{π}{2 - 3 x}) - 1] s e c^{2} (\frac{π}{2 - 5 x})}$

$= e^{\underset{x \to 0}{l i m} \frac{- s i n^{2} (\frac{- 3 π x}{2 (2 - 3 x)})}{s i n^{2} (\frac{- 5 π x}{2 (2 - 5 x)})}} = e^{- \frac{9}{25}}$

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a year ago

Class 12th Physics

A point object moves towards a concave mirror with a speed $10 c m s^{- 1}$ along the principal axis. The magnitude of the velocity of object with respect to image when the object is at distance of 15cm from the pole is __ $c m s^{- 1}$ . (Focal length of the mirror kept at rest is 10cm )