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Chemistry Class 12th

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]

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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

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

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Chemistry Class 12th

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

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Payal Gupta

Contributor-Level 10

XeO₃ ⇒ Number of lone pair = 1

XeOF₄ ⇒ Number of lone pair = 1

XeF₆ ⇒ Number of lone pair = 1

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Chemistry 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.

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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

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Chemistry Class 11th

While performing a thermodynamics experiment, a student made the following observation.

HCl + NaOH → NaCl + H₂O $Δ H$ = -57.3 kJ mol^?1

CH₃COOH + NaOH → CH₃COONa + H₂O $Δ H$ = -55.3 kJ mol^-1

The enthalpy of ionization of CH₃COOH as calculated by the student is _________kJ mol^-1. (nearest integer)

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Payal Gupta

Contributor-Level 10

$Δ H_{i o n i z a t i o n} o f C H_{3} C O O H = - 55.3 (- 57.3)$

= 2 KJ/mole

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Chemistry Class 12th

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

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Payal Gupta

Contributor-Level 10

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

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Chemistry Class 11th

A sealed flask with a capacity of 2 dm³ contains 11g of propane gas. The flask is so weak that it will burst if the pressure becomes 2 MPa. The minimum temperature at which the flask will burst is _________ $° C$ . [Nearest integer]

(Given: R = 8.3 JK^-1 mol^-1. Atomic masses of C and H are 12u and 1u, respectively)

(Assume that propane behaves as an ideal gas.)

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Payal Gupta

Contributor-Level 10

V = 2 $l$ , n = 0.25 Moles, P = 2 * 106 Pa, R = 8.314 J/mol.k

PV = nRT

$2 * 1 0^{6} * 2 * 1 0^{- 3} = 0.25 * 8.314 * T$

T = 1654.7 $\approx$ 1655 K

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a year ago

Chemistry Chemistry Some Basic Concepts of Chemistry

56.0L of nitrogen gas is mixed with excess of hydrogen gas and it is found that 20L of ammonia gas is produced. The volume of unused nitrogen gas is found to be _______L.

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Payal Gupta

Contributor-Level 10

$N_{2} (g) + 3 H_{2} (g) \to 2 N H_{3} (g)$

t = 0 56 $l$ Excess 0

-10 $l$ +20 $l$

Final 46 $l$ 20 $l$

Vol. of N₂ (g) remained unreacted = 46 $l$

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Chemistry VSEPR Theory

What do you understand by bond pairs and lone pairs of electrons? Illustrate by giving one example of each type.

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Satyendra Dhyani

Beginner-Level 5

Molecules usually form chemical bond through either sharing or through rtransfering the electrons. During covalent bonding the electron pairs shared between atoms to form covalent bond are called shared pair or bond pair. At the same time, the electron pair which is not involved in sharing is called lone pair of electrons.

For example: CH₄ has 4 bond pairs but H₂O has 2 bond pairs and 2 lone pairs.

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Chemistry VSEPR Theory

What is VSEPR theory in class 11th Chemistry?

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Esha Garg

Beginner-Level 5

The Valence Shell Electron Pair Repulsion (VSEPR) Theory is an algorithm developed to predict the molecular geometry of the compounds. The VSEPR theory predict the molecular shape based on the repulsion between electron pairs (bonding and lone) around the central atom. As per the NCERT Textbooks:

“According to this theory, the shape of a molecule depends upon the number of valence shell electron pairs around the central atom. Electron pairs repel each other and try to remain as far apart as possible to minimise repulsion, thus determining the geometry of the molecule.”

You can use this theory in primarily explaining the molecular str

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Chemistry VSEPR Theory

What are the 5 postulates of VSEPR theory?

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Piyush Vimal

Beginner-Level 5

VSEPR theory predicts the shape of molecule based on postulate (assmptions). here are the important postulates as per the NCERT textbooks.

The molecular geometry shape depends upon the number of valence shell electron pairs (bonded and non-bonded) around the central atom.
The electron pairs (bonded and lone pairs) in the valence shell repel each other since their electron clouds are negatively charged.
These electron pairs arrange themselves to minimize repulsion so that the molecule attains a stable structure with minimum energy.
All electron pair repulsion doesn't repel each other equally, Electron pairs follows this order:
Lone pai

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