Class 11th

A system does 200 J of work and at the same time absorbs 150 J of heat. The magnitude of the change in internal energy is __________ J. (Nearest integer)

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Contributor-Level 10

q = +150 J
w = -200 J
∴ ΔU = q + w = 150 - 200 = -50 J
So, magnitude of ΔU is 50 J.

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2 months ago

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Lithium halides are some what covalent is nature.
Reason R: Lithium possess high polarisation capability.
In the light of the above statements, choose the most appropriate answer from the options given below:

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Class 11th Chemistry Organic Chemistry

Contributor-Level 10

Due to small size Li have more polarizing power so most of the compound of Li are covalent.

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2 months ago

The correct order of stability of given carbocations is:

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Contributor-Level 10

Order of stability is,

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Assuming that Ba(OH)₂ is completely ionized in aqueous solution under the given conditions the concentration of H₃O⁺ ions in 0.005 M aqueous solution of Ba(OH)₂ at 298 K is __________ * 10⁻¹² mol L⁻¹. (nearest integer)

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Contributor-Level 10

Ba (OH)? ? Ba? ² + 2 (OH)?
Initial: 0.005M, 0, 0
Final: 0, 0.005, 0.010
[OH? ] = 0.01 M = 10? ² M
Kw = [H? ] [OH? ]
[H? ] or [H? O? ] = Kw/ [OH? ] = 10? ¹? /10? ² = 10? ¹² M
∴ [H? O? ] = 1 * 10? ¹² M

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2 months ago

Match List- I with List-II:

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Contributor-Level 10

NaOH - Base
Be (OH)? - Amphoteric
Ca (OH)? - Base
B (OH)? - Acidic
Al (OH)? - Amphoteric

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Class 11th Structure of Atom

The ionic radii of K?, Na?, Al³? and Mg²? are in the order

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Raj Pandey

Contributor-Level 9

When positive charge increases, ionic radii decreases in isoelectronic ions
Al?³ < Mg? < Na? < K?

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An accelerated electron has speed of 5*10⁶ ms⁻¹ with an uncertainty of 0.02%. The uncertainty in finding its location while in motion is x * 10⁻⁹m. The value of x is __________.
(Nearest integer)
[Use mass of electron = 9.1*10⁻³¹ kg, h = 6.63*10⁻³⁴ Js, π=3.14]

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Contributor-Level 10

Δx . Δp = h/4π
Δx . mΔv = h/4π
Δv = 5 * 10? * 0.02/100 = 1000 m/s
∴ Δx = h/ (4πmΔv) = 6.63*10? ³? / (4*3.14*9.1*10? ³¹*1000)
= 5.8 * 10? m
= 58 * 10? m.

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2 months ago

Class 11th Redox Reactions

Presence of which reagent will affect the reversibility of the following reaction, and change it to a irreversible reaction:
CH? + I? ? CH?I + HI (Reversible)

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Contributor-Level 10

CH? + I? CH? I + HI
It is reversible due to reducing nature of HI but it can be irreversible by addition of oxidizing agents like, HNO? , HIO? , HgO, etc. which will oxidize HI into I?

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2 months ago

An LPG cylinder contains gas at a pressure of 300 kPa at 27°C. The cylinder can withstand the pressure of 1.2*10? Pa. The room in which the cylinder is kept catches fire. The minimum temperature at which the bursting of cylinder will take place is __________ °C. (Nearest integer)

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Contributor-Level 10

P? = 300 kPa = 3 * 10? Pa = 3 bar
T? = 300 K
P? = 1.2 * 10? Pa = 12 * 10? Pa = 12 bar
T? =?
P? /T? = P? /T?
3/300 = 12/T?
T? = (12 * 300)/3 K = 1200 K
∴ T in °C = 1200 - 273 = 927°C

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2 months ago

The number of significant figure in 0.00340 is __________.

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