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4 years ago

Control over nitrogenase activity is accomplished by which of the following?

Chemistry

1 answer:

SIZIF [17.4K]4 years ago

5 0

Answer:

Explanation:

Control over nitrogenase activity is accomplished by NH4+ prevents expression of the genes that encode nitrogenas.

Nitrogenase synthesis in free-living N2-fixing bacteria is universally under repressor control by ammonia. This, however, is not

the case for rhizobia. A need for N2 as inducer apparently does not

exist. The degree of ammonia repression is unusual in its strength.

Nitrogenase activity is at least 1O,OOO-fold lower in extracts of

NH4+-grown cells versus N2-grown cells.

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3 years ago

1. The red light associated with the aurora borealis is emitted by excited oxygen atoms. This

stiv31 [10]

Answer:

Frequency = 0.005× 10¹⁷ s⁻¹

E = 0.03 × 10⁻²⁰KJ

Explanation:

Given data:

Wavelength of light = 630.0 nm (630 × 10⁻⁹ m)

Frequency of light = ?

Energy in joule = ?

Solution:

speed of light = wavelength × frequency

Frequency = speed of light / wavelength

Frequency = 3 × 10⁸ m/s / 630 × 10⁻⁹ m

Frequency = 0.005× 10¹⁷ s⁻¹

Energy:

E = h. f

E = 6.63× 10⁻³⁴ Kg. m²/s × 0.005× 10¹⁷ s⁻¹

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E = 0.03 × 10⁻¹⁷ j×1 kj /1000 j

E = 0.03 × 10⁻²⁰KJ

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3 years ago

Given: 2H2O2 → 2H2O + O2 structure of H2O2: H–O–O–H Bond Bond Energy (kJ/mol) O–H 459 O=O 494 O–O 142 Based on the given bond en

ICE Princess25 [194]

Answer:

B. - 210 kJ

Explanation:

∵ ΔHrxn = ∑(bond energies)products - ∑(bond energies)reactants.

The bond formation in the products releases energy (exothermic).

The bond breaking in the reactants requires energy (endothermic).

The products:

H₂O contains 2 O-H (- 459 kJ/mol) bonds.

O₂ contain 1 O=O (- 494 kJ/mol) bond.

The reactants:

H₂O₂ contain 2 O–H (459 kJ/mol) bonds and 1 O–O (142 kJ/mol) bond.

∵ ΔHrxn = ∑(bond energies)products - ∑(bond energies)reactants.

∴ ΔHrxn = [2 (2 x (O–H bond energy) + (1 x (O=O bond energy)] - 2 [(2 x (O–H bond energy) + (1 x (O–O bond energy)] = [2 (2 x - 459 kJ/mol) + (1 x - 494 kJ/mol)] - 2 [(2 x 459 kJ/mol) + (1 x 142 kJ/mol)] = (- 2330 kJ) + (2120 kJ) = - 210 kJ.

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3 years ago

Write the empirical formula of at least four binary ionic compounds that could be formed from the following ions: Zn2+, Ni4+, F-

hram777 [196]

Ionic compounds are formed between oppositely charged ions.

A binary ionic compound is composed of ions of two different elements - one of which is a positive ion(metal), and the other is negative ion (nonmetal).

To write the empirical formula of binary ionic compound we must remember that one ion should be positive and other ion should be negative, then only the correct formula should be written. To write the empirical formula the charges of opposite ions should be criss-crossed.

First empirical formula of binary ionic compound is written between $Zn^{2+} (Positive ion)and F^{-} (Negative ion)$

First Formula would be $ZnF_{2}$

Second empirical formula is between $Zn^{2+}(Positive ion) and O^{2-}(Negative ion)$

Second Formula would be $Zn_{2}O_{2}$

Note : When the subscript are same they get cancel out, so $Zn_{2}O_{2}$ would be written as $ZnO$

Third empirical formula is between $Ni^{4+}(Positive ion) and F^{-}(Negative ion)$

Third Formula would be : $NiF_{4}$

Forth empirical formula is between $Ni^{4+}(Positive ion)and O^{2-}(negative ion)$

Forth Formula would be : $Ni_{2}O_{4}$ or $NiO_{2}$

Note- The subscript will be simplified and the formula will be written as $NiO_{2}$ .

The empirical formula of four binary ionic compounds are : $ZnF_{2}, ZnO, NiF_{4},NiO_{2}$

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Viktor [21]

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