URGENT PLEASE ANSWER

How many atoms are in a sample of chromium with a mass of 31 grams? O a 2.4 x 1024 atoms of chromium b 3.6 x 1023 atoms of chrom

lukranit [14]

Answer:

b. 3.66x10²³ atoms of chromium.

Explanation:

First we calculate how many moles are there in 31 grams of chromium, using its molar mass:

Molar Mass of Chromium = 51 g/mol (This can be found on any periodic table)

31 g ÷ 51 g/mol = 0.608 mol

Then we calculate how many atoms are there in 0.608 moles, using Avogadro's number:

0.608 mol * 6.023x10²³ atoms/mol = 3.66x10²³ atoms

The correct answer is thus option b. 3.66x10²³ atoms of chromium.

4 0

2 years ago

Define the term Symmetry? and explain its types

nika2105 [10]

Answer:

Mathematically, symmetry means that one shape becomes exactly like another when you move it in some way: turn, flip or slide. ... There are three basic types of symmetry: rotational symmetry, reflection symmetry, and point symmetry.

5 0

3 years ago

Part 1: A cylinder containing 20.0 L of compressed nitrogen is connected to an empty (evacuated) vessel with an unknown volume.

baherus [9]

Answer:

The volume of the vessel is 250 L

Partial pressure of hydrogen = 189 torr

Explanation:

Using Boyle's law

${P_1}\times {V_1}={P_2}\times {V_2}$

Given ,

V₁ = 20.0 L

V₂ = ?

P₁ = 25 atm

P₂ = 2 atm

Using above equation as:

${P_1}\times {V_1}={P_2}\times {V_2}$

${25}\times {20.0}={2}\times {V_2}$

${V_2}=\frac {{25}\times {20.0}}{2}\ L$

${V_2}=250\ L$

The volume of the vessel is 250 L.

According to Dalton's law of partial pressure:-

$P_{H_2}=Mole\ fraction\times Total\ Pressure$

So, according to definition of mole fraction:

$Mole\ fraction\ of\ H_2=\frac {n_{H_2}}{n_{H_2}+n_{He}}$

Also,

Mole fraction of H₂ = 1 - Mole fraction of He = 1 - 0.75 = 0.25

So,

Total pressure = 756 torr

Thus,

$P_{H_2}=0.25\times 756\ torr$

Partial pressure of hydrogen = 189 torr.

7 0

3 years ago

During an experiment, the percent yield of calcium chloride from a reaction was 82.38%. Theoretically, the expected amount shoul

gregori [183]

Answer:

Actual yield = 86.5g

Explanation:

Percent yield = 82.38%

Theoretical yield = 105g

Actual yield = x

Equation of reaction,

CaCO₃ + HCl → CaCl₂ + CO₂ + H₂O

Percentage yield = (actual yield / theoretical yield) * 100

82.38% = actual yield / theoretical yield

82.38 / 100 = x / 105

Cross multiply and make x the subject of formula

X = (105 * 82.38) / 100

X = 86.499g

X = 86.5g

Actual yield of CaCl₂ is 86.5g

7 0

3 years ago

Is the photon is in the IR, UV or visible portion of the electromagnetic spectrum.

DiKsa [7]

Answer:

The different types of radiation are defined by the the amount of energy found in the photons. Radio waves have photons with low energies, microwave photons have a little more energy than radio waves, infrared photons have still more, then visible, ultraviolet, X-rays, and, the most energetic of all, gamma-rays.Explanation: hope this helps god bless you

8 0

2 years ago