Help me please !!!

Select the correct answer from each drop-down menu.

postnew [5]

Answer:

Among the different types of scientific knowledge hypotheses are likely to be modified or discarded most frequently. Long ago in the 1600's scientists discarded the phlogiston theory because the new evidence didnt support it.

Explanation:

Hypothesis is the assumption of something possible or impossible to draw a consequence and is provisionally established as the basis for an investigation and which can confirm or deny its validity. For this reason, within scientific research, hypotheses are so important and so changeable that they are modified or discarded more frequently within scientific knowledge.

Based on a work by Johann Joachim Becher, the German scientist Georg Ernst Stahl created the phlogiston theory that said combustion occurred with certain materials because they had an “element” or a common flammable principle that was released at the time of burning . This theory was abandoned because there was no evidence, even through scientific experiments, to prove that this theory is true.

8 0

3 years ago

Which of the following are diatomic elements? Select all that apply.

TiliK225 [7]

Answer:

C

Explanation:

A diatomic element in that list is Bromine

8 0

2 years ago

Sulfur undergoes combustion to yield sulfur trioxide by the following reaction equation:

12345 [234]

Answer:

Therefore, the amount of heat produced by the reaction of 42.8 g S = <u>(-5.2965 × 10²) kJ = (-5.2965 × 10⁵) J</u>

Explanation:

Given reaction: 2S + 3O₂ → 2 SO₃

Given: The enthalpy of reaction: ΔH = - 792 kJ

Given mass of S: w₂ = 42.8 g, Molar mass of S: m = 32 g/mol

In the given reaction, the number of moles of S reacting: n = 2

As, Number of moles: $n = \frac{mass\: (w_{1})}{molar\: mass\: (m)}$

∴ mass of S in 2 moles of S: $w_{1} = n \times m = 2\: mol \times 32\: g/mol = 64\: g$

<em>Given reaction</em>: 2S + 3O₂ → 2 SO₃

<em>In this reaction, the limiting reagent is S</em>

⇒ 2 moles S produces (- 792 kJ) heat.

or, 64 g of S produces (- 792 kJ) heat.

∴ 42.8 g of S produces (x) amount of heat

⇒ <u><em>The amount of heat produced by 42.8 g S:</em></u>

$x = \frac{(- 792\: kJ) \times 42.8\: g}{64\: g} = (-529.65)\: kJ$

$\Rightarrow x = (-5.2965 \times 10^{2})\: kJ = (-5.2965 \times 10^{5})\: J$

$(\because 1 kJ = 10^{3} J)$

<u>Therefore, the amount of heat produced by the reaction of 42.8 g S = (-5.2965 × 10²) kJ = (-5.2965 × 10⁵) J</u>

8 0

3 years ago

_____________ is an acronym used to refer a family of iron alloys.

Daniel [21]

FeNi or NiFe is an acronym used to refer a family of iron alloys.

<h3>What is alloy?</h3>

An alloy is a mixture of chemical elements that contains at least one is a metal.

<h3>Alloy of iron</h3>

The alloy of iron-nickel can be abbreviated as FeNi, which implies iron-nickel.

where;

Fe stands for iron
Ni stands for Nickel

Thus, FeNi or NiFe is an acronym used to refer a family of iron alloys.

Learn more about iron alloys here: brainly.com/question/24842164

5 0

2 years ago

You have a 250. -ml sample of 1. 28 m acetic acid (ka = 1. 8 x´ 10–5). calculate the ph of the best buffer.

Nadya [2.5K]

The ph of the best buffer is 4.74

The given acetic acid is a weak acid

The equation of the pH of the buffer

pH = pKa + log ( conjugate base / weak acid ).

For best buffer the concentration of the weak acid and its conjugate base is equal.

pH = pKa + log 1

pH = pKa + 0

pH = pKa

given Ka = 1.8 × 10⁻⁵

pKa = - log ka

pH = -log ( 1.8 × 10⁻⁵ )

pH = 4. 74

Hence the pH of the best buffer is 4.74

Learn more about the pH on

brainly.com/question/22390063

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4 0

2 years ago

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