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3 years ago

In which environment would primary succession take place? Select 2 options.

Chemistry

2 answers:

kotegsom [21]3 years ago

7 0

Answer:

a cooling lava flow

a deserted mine

Explanation:

kumpel [21]3 years ago

7 0

Answer:

<em><u>an abandoned field, a cooling lava flow, a valley under a glacier, and an unused farm</u></em>

Explanation:

Primary succession happens in a place where there is no soil cover or it is removed.

an abandoned field- Secondary; because there is cover of soil left, even if vegetation is removed.

a cooling lava flow- Primary; volcanic events lead to loss of soil layer, so this would lead to primary succession

a valley under a glacier- Primary; retreating glaciers are lead to primary succession

an unused farm-Secondary; the soil cover is still present

a burnt forest- Secondary; soil cover is still left for vegetation to start over again

a deserted mine- Primary; because there would be barren rocks left, so soil would be formed by pioneer species first.

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A chemical reaction was carried out three times. The mass of the product was 8.93 g for the first trial, 8.94 g for the second t

joja [24]

The three mass value measure are precise mass

<u>explanation</u>

precise mass is term use to describe data from experiment that have been repeated several times. An experiment that yield tightly grouped set of data it has a high precision. 8.93 , 8.94 and 8.92 are precise mass since they have repeated severally

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4 years ago

an atmosphere is considered hazardous if it contains a hazardous gas in excess of 10 percent of the hazardous material's:

svlad2 [7]

Lower flammable limit means the lowest concentration of a material that will propagate a flame.

What is hazardous atmosphere?

It is an atmosphere that may expose employees to risk of death, incapacitation, impairment of ability to self-rescue, injury, or acute illness from one or more of following causes

Flammable gas, vapor, or mist in excess of 10 percent of lower flammable limit (LFL)
Airborne combustible dust at concentration that meets or exceeds its LFL

What is lower flammable limit?

It means the lowest concentration of a material that will propagate a flame.
The LFL is usually expressed as percent by volume of material in air (or other oxidant)
Atmospheres with concentration of flammable vapors at or above 10 percent of lower explosive limit (LEL) are considered hazardous when located in confined spaces.
However, atmospheres with flammable vapors below 10 percent of LEL are not necessarily safe. Such atmospheres are too lean to burn

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6 0

1 year ago

1,670,000,000 in<br> scientific notation pleaseeee

noname [10]

Answer:

1.67 × 10^9

Explanation:

6 0

3 years ago

Read 2 more answers

3. In an experiment it was found that 40.0cm of 0.2M sodium hydroxide solution just neutralized 0.2g

hjlf

The relative molecular mass of acid A : 50 g/mol

<h3>Further explanation</h3>

Given

40.0 cm³(40 ml) of 0.2M sodium hydroxide

0.2g of a dibasic acid

Required

the relative molecular mass of acid A

Solution

Titration formula

M₁V₁n₁=M₂V₂n₂

n=acid/base valence(number of H⁺/OH⁻)

NaOH ⇒ n = 1

Dibasic acid = diprotic acid (such as H₂SO₄)⇒ n = 2

mol = M x V

Input the value in the formula :(1 = NaOH, 2=dibasic acid)

0.2 x 40 x 1 = M₂ x V₂ x 2

M₂ x V₂ = 4 mlmol = 4.10⁻³ mol ⇒ mol of Acid A

The relative molecular mass of acid A (M) :

$\tt M_A=\dfrac{mass }{mol}=\dfrac{0.2~g}{4.10^{-3}}=50~g/mol$

5 0

3 years ago

An unknown compound, X is thought to have a carboxyl group with a pKa of 2.0 and another ionizable group with a pKa between 5 an

Westkost [7]

Answer:

7.3

Explanation:

By Henderson Hasselbalch equation we can calculate the pH or the pOH of a solution by its pKa. Remember that $pH = -log[H^{+}]$ , and pKa = -logKa. Ka is the equilibrium constant of the acid.

Henderson Hasselbalch equation :

$pH = pKa - log \frac{[HA]}{[A^{-}]}$

Where [HA] is the concentration of the acid, and $[A^{-}]$ is the concentration of the anion which forms the acid.

So, acid X, has two ionic forms, the carboxyl group and the other one. First, we have 0.1 mol/L of the acid, in 100 mL, so the number of moles of X

n1 = (0.1 mol/L)x(0.1 L) = 0.01 mol

When it dissociates, it forms 0.005 mol of the carboxyl group and 0.005 mol of the other group. Assuming same stoichiometry.

Adding NaOH, with 0.1 mol/L and 75 mL, the number of moles of $OH^-$ will be

n2 = (0.1 mol/L)x(0.075 L) = 0.0075 mol

So, the 0.0075 mol of $OH^-$ reacts with 0.005 mol of carboxyl, remaining 0.0025 mol of $OH^-$ , which will react with the 0.005 mol of the other group. So, it will remain 0.0025 mol of the other group.

The final volume of the solution will be 175 mL, but both concentrations (the acid form and ionic form) have the same volume, so we can use the number of mol in the equation.

Note that, the number of moles of the acid form is still 0.01 mol because it doesn't react!

So,

$6.72 = pKa - log \frac{0.01}{0.0025}$

6.72 = pKa - log 4

pKa - log4 = 6.72

pKa = 6.72 + log4

pKa = 6.72 + 0.6

pKa = 7.3

8 0

3 years ago