Class 11th

Boiling of hard water is helpful in removing the temporary hardness by converting calcium hydrogen carbonate and magnesium hydrogen carbonate to

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Contributor-Level 10

During removal of temporary hardness of water.

$\begin{array}{l} M g {(H C O_{3})}_{2} \overset{B o i l}{\to} M g {(O H)}_{2} + 2 C O_{2} ↑ \\ C a {(H C O_{3})}_{2} \overset{B o i l}{\to} C a C O_{3} + H_{2} O + C O_{2} \end{array}$

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10 months ago

Identify the correct statement from B₂H₆ from those given below :

(A) In B₂H₆, all B-H bonds are equivalent

(B) In B₂H₆, there are four 3-centre 2- electron bonds

(C) B₂H₆ is a Lewis acid

(D) B₂H₆ can be synthesized from both BF₃ and NaBH₄.

(E) B₂H₆ is planar molecule.

Choose the most appropriate answer from the options given below :

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Class 11th Chemistry Classification of Elements and Periodicity in Properties

Contributor-Level 10

B₂H₆ has 4 2 c -2e bonds and 2 3c-2e bonds.

Bridging (B-H) bonds have more value of bond- length then terminal (B – H) bonds

Bridging bonds are in one plane, but terminal bonds are in perpendicular plane.

Due to presence of (3c-2e) bonds, it behaves as electrons deficient and prone to get attached by lewis base.

$3 N a B H_{4} + 4 B F_{3} ?_{}^{?} 3 N a B F_{4} + 2 B_{2} H_{6}$

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10 months ago

Which of the following elements is considered as a metalloid?

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Contributor-Level 10

Except Te, all are metals.

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10 months ago

Which of the following statements are correct?

(A) Both LiCl and MgCl₂ are soluble in ethanol

(B) The oxides Li₂O and MgO combine with excess of oxygen to give superoxide.

(C) LiF is less soluble in water than other alkali metal fluorides.

(D) Li₂O is more soluble in water than other alkali metal oxides.

Choose the most appropriate answer from the options given below :

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Contributor-Level 10

Due to higher extent of polarization by Li⁺ and Mg²⁺, LiCl and Mgcl₂ have covalent character. Therefore they are soluble in ethanol.

Due to very high value of lattice energy, LiF is having very less solubility in water.

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10 months ago

The highest industrial consumption of molecular hydrogen is to produce compounds of element :

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Contributor-Level 10

The highest industrial consumption of hydrogen gas is in the synthesis of ammonia gas (Having manufacturing of N-based fertizers)

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10 months ago

The highest industrial consumption of molecular hydrogen is to produce compounds of element :

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Contributor-Level 10

The highest industrial consumption of hydrogen gas is in the synthesis of ammonia gas (Having manufacturing of N-based fertizers)

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10 months ago

On complete combustion of 0.492g of an organic compound containing C, H and O, 0.7938 g of CO₂ and 0.4428 g of H₂O was produced. The % composition of oxygen in the compounds is____________.

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% of C in organic compound

$= \frac{12}{14} * \frac{W C O_{2}}{W . O . C .} * 100$

$= \frac{952.56}{21.648} = 44 %$

$% o f H = \frac{2}{18} * \frac{W H_{2} O}{W . O . C .} * 100$

= $\frac{20}{18} * \frac{0.4428}{0.492} * 100$

= $\frac{88.56}{8.856} = 10 %$

= 100 – 54 = 46%

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10 months ago

The number of radial land angular nodes in 4d orbital are, respectively

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Class 11th Units and Measurement

Contributor-Level 10

In 4d orbital, n = 4 and $l = 2$

Radial nodes = $n - l - 1$

Radial nodes = 4 – 2 – 1 = 1

And angular nodes, $l = 2$

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10 months ago

In an experiment to determine the Young's modulus of wire of a length exactly 1m, the extension in the length of the wire is measured as 0.4mm with an uncertainty of $\pm$ 0.02mm when a load of 1kg is applied. The diameter of the wire is measured as 0.4mm with an uncertainty of $\pm$ 0.02mm. The error in the measurement of Young's modulus $(Δ Y)$ is found to be x * 10¹⁰Nm^-2. The value of x is _________.

(take g = 10 ms^-2)

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Class 11th Physics System of Particles and Rotational Motion

Contributor-Level 10

L = 1 m

$Δ L = 0.4 * 1 0^{- 3} m$

$m = 1 k g$

d = 0.4 * 103 m

$\frac{F}{A} = y \frac{Δ L}{L}$

$y = \frac{F L}{A Δ L} = \frac{(m g) * 1}{(\frac{π d^{2}}{4}) * 0.4 * 1 0^{- 3}}$

$Δ y = 0.1 * 0.199 * 1 0^{12} = 1.99 * 1 0^{10}$

= 1.99

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10 months ago

A disc of mass 1kg and radius R is free to rotate about a horizontal axis passing through its centre and perpendicular to the plane of disc. A body of same mass as that of disc is fixed at the highest point of the disc. Now the system is released, when the body comes to the lowest position, its angular speed will be $\sqrt[]{\frac{x}{3 R} r a d s^{- 1}}$ where x = __________.

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