Which of the following is not used when analyzing and evaluating scientific explanations?

mina [271]

Answer: B

Explanation: I had an even lengthier explanation but Brainly is being a butthead. But I got it right on my test for those who want to know.

7 0

2 years ago

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Naturally occurring element X exists in three isotopic forms: X-28 (27.979 amu, 92.21% abundance), X-29 (28.976 amu 4.70% abunda

bezimeni [28]

Answer: The average atomic mass of X is 28.09 amu

Explanation:

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

$\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i$ .....(1)

For isotope 1:

Mass of isotope 1 = 27.979 amu

Percentage abundance of isotope 1 = 92.21 %

Fractional abundance of isotope 1 = 0.9212

For isotope 2:

Mass of isotope 2 = 28.976 amu

Percentage abundance of isotope 2 = 4.70 %

Fractional abundance of isotope 2 = 0.0470

For isotope 3:

Mass of isotope 3 = 29.974 amu

Percentage abundance of isotope 3 = 3.09 %

Fractional abundance of isotope 3 = 0.0309

Putting values in equation 1, we get:

$\text{Average atomic mass of X}=[(27.979\times 0.9212)+(28.976\times 0.0470)+(29.974\times 0.0309)]$

$\text{Average atomic mass of X}=28.09amu$

Hence, the average atomic mass of X is 28.09 amu

4 0

2 years ago

A material has a volume of 63.0 cm3 and a mass of 28 grams. What is the density of the material in g/cm3 to the correct number

dimaraw [331]

Answer:

0.4444 g/cm³ ≅ 0.44 g/cm³ (2 significant figures).

Explanation:

Knowing that:

d = m/V,

where, d is the density of the material (g/cm³).

m is the mass of the material (m = 28 g).

V is the volume of the material (V = 63.0 cm³).

∴ d = m/V = (28 g)/(63.0 cm³) = 0.4444 g/cm³ ≅ 0.44 g/cm³ (2 significant figures).

7 0

2 years ago

Given 6.98 x 10 4 power grams of iron, calculate the moles of iron present

KiRa [710]

Answer:

1249.88 mol.

Explanation:

∵ no. of moles of Fe = mass of Fe/atomic weight of Fe.

∴ no. of moles of Fe = (6.98 x 10⁴ g)/(55.845 g/mol) = 1249.88 mol.

6 0

2 years ago

Is the following nuclear equation balanced? 237 Np - He+233 AM

Flura [38]

Answer:

Yes

Explanation:

Np²³⁷ → He⁴ + Am²³³

The given nuclear equation is balanced. Np²³⁷ undergoes alpha decay and produce alpha particle and Am²³³.

Properties of alpha radiation:

Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. Which is also called helium nuclei. When atom undergoes the alpha emission the original atom convert into the atom having mass number 4 less than and atomic number 2 less than the starting atom.

Alpha radiations can travel in a short distance.

These radiations can not penetrate into the skin or clothes.

These radiations can be harmful for the human if these are inhaled.

These radiations can be stopped by a piece of paper.

₉₂U²³⁸ → ₉₀Th²³⁴ + ₂He⁴ + energy

6 0

2 years ago