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torisob [31]
2 years ago
12

8. Which of the following have bacteria in their root nodules that fix nitrogen?

Chemistry
1 answer:
Natalka [10]2 years ago
8 0

Answer:

Option A

Explanation:

Leguminous plants like pulses etc. have root nodules comprising of rhizobacterium which live in a symbiotic relationship with the roots of the plant and in turn fix the nitrogen in the soil in the roots of the leguminous plants.

Hence, option A is correct

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What do scientists call all of the compounds that contain carbon and are found in living things?
Stella [2.4K]
Organic is the answer
5 0
3 years ago
I NEED HELP!!!
True [87]

Answer:

Explanation:

Formula

Heat = m * c * delta t

t = temperature in centigrade.

The first thing you have to do is convert kelvin degrees to centigrade. The conversion factor is - 273. The formula is degrees centigrade = degrees kelvin - 273. It is easier to understand with a couple of examples.

  • 290o K = 290 - 273 = 17
  • 325. K =   325 - 273 = 52

Solution

Heat = 100.0 grams * 4.18 J/g*C * (52 - 17)

Heat = 100 * 4.18 * 35

Heat = 14630 Joules

But you want kj

Heat = 14630 / 100 = 14.63

Answer

Heat = 14.6 kj

6 0
2 years ago
Find the initial concentration of the weak acid or base in each of the following aqueous solutions: (a) a solution of HClO with
Luda [366]

Answer:

a) 0.021 M

b) 0.019 M

Explanation:

To do this, you need to calculate the concentration of ions in solution with the given value of pH for each solution, then, write the chemical equation for both solutions, Set an ICE chart, use the value of Ka and Kb reported for both solutions, and solve for the initial concentration.

This is the general procedure to do it, now let's do it by parts.

<em><u>a) Concentration of HClO pH = 4.6</u></em>

With the given pH, we use the following expression:

pH = -log[H₃O⁺]      From here, we solve for [H₃O⁺]

[H₃O⁺] = 10^(-pH)   (1)

Let's calculate first the hydronium concentration:

[H₃O⁺] = 10^(-4.6) = 2.51x10⁻⁵ M

This value indicates the equilibrium concentration of this ion in solution. Now, to know the initial concentration of the acid, we need to do an ICE chart and write the chemical equation. This is an acid - base reaction, so we need the value of Ka of the acid.

         HClO + H₂O <---------> H₃O⁺ + ClO⁻       Ka = 3x10⁻⁸

I:            Y                                 0          0

C:          -x                                +x         +x

E:           Y - x                            x          x

With this chart, we need to write the expression for Ka which is:

Ka = [H₃O⁺] * [ClO⁻] / [HClO] = x² / Y-x

But we already know the concentration of [H₃O⁺], which is the same for [ClO⁻], and the value of Ka, so all we have to do is replace the values in the above expression and solve for Y:

3x10⁻⁸ = (2.51x10⁻⁵)² / Y - 2.51x10⁻⁵

We can round to Y because "x" is a very small value as it's value of Ka so:

3x10⁻⁸ = (2.51x10⁻⁵)²/Y

Y = (2.51x10⁻⁵)²/3x10⁻⁸

<h2><em>Y = [HClO] = 0.021 M</em></h2>

<em>And this is the initial concentration of the acid.</em>

<u><em>b) Solution of hidrazine pH = 10.2</em></u>

We do the same procedure as part a) with the difference that instead of using Ka , we use Kb and concentration of [OH⁻]. The Kb for hydrazine is 1.3x10⁻⁶

Let's calculate the [OH⁻]:

pOH = 14 - pH

pOH = 14 - 10.2 = 3.8

[OH⁻] = 10^(-3.8) = 1.58x10⁻⁴ M

The chemical equation:

          N₂H₄ + H₂O <---------> N₂H₅⁺ + OH⁻    Kb = 1.3x10⁻⁶

I:            Y                                  0           0

C:          -x                                +x           +x

E:         Y-x                                 x           x

Kb = x²/(Y-x)

1.3x10⁻⁶ = (1.58x10⁻⁴)²/Y

Y = (1.58x10⁻⁴)²/1.3x10⁻⁶

<h2><em><u>Y = [OH⁻] = 0.019 M</u></em></h2>

And this is the initial concentration of hydrazine

4 0
3 years ago
Niels Bohr's model of the hydrogen atom was controversial because _________.a. it contradicted accepted principles of physics. b
Tju [1.3M]

Answer:

The correct answer to the question is

a. it contradicted accepted principles of physics

Explanation:

The idea of electrons moving in orbits contradict classical electromagnetism idea whereby electrons are expected spiral to the nucleus instantaneously. Meaning all atoms are supposed to be unstable a postulation that contradicts observable evidence.

Bohr's model of the atom consists of atoms, having electrons in specific orbits. The theory explains spectroscopy and enabled the determination of the constituent atoms present in distant stars.

5 0
3 years ago
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A cactus needle is a structure made of different tissues that work together to protect the plant from animals that might want to
Nezavi [6.7K]
Organ, it’s made of tissue, and also it’s out
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3 years ago
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