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2 years ago

Helppppppppppppppppp

Chemistry

2 answers:

Sonbull [250]2 years ago

7 0

The correct answer is E.

musickatia [10]2 years ago

4 0

Answer:

I think it's B

Explanation:

Brainlest po

Maybe i been learn this before

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HELPPPPP PLEASEEE ILL MARK YOU BRAINLIESTTTTTT!!!!!!!!!!!!!!!!!!!!!!!!!!

azamat

Answer:

Ionic bonding occurs when atoms either gain or lose one or more valence electrons, resulting in the atom having either a negative or positive charge.

Through ionic bonding, an atom of each element will combine with the other to form a molecule, which is more stable since it now has a zero charge.

Explanation:

6 0

3 years ago

Read 2 more answers

One crystalline form of silica (SiO2) has a cubic unit cell, and from X-ray diffraction data it is known that the cell edge leng

Sav [38]

Answer:

8 Silicon atom are present in unit cell.

16 oxygen atoms are present unit cell.

Explanation:

Number of atoms in unit cell = Z =?

Density of silica = tex]2.32 g/cm^3[/tex]

Edge length of cubic unit cell = a = 0.700 nm = $0.700\times 10^{-7} cm$

$1 nm=10^{-7} cm$

Molar mass of Silica = $28.09 g/mol+16.00\times 2=60.09 g/mol$

Formula used :

$\rho=\frac{Z\times M}{N_{A}\times a^{3}}$

where,

$\rho$ = density

Z = number of atom in unit cell

M = atomic mass

$(N_{A})$ = Avogadro's number

a = edge length of unit cell

On substituting all the given values , we will get the value of 'a'.

$2.32 g/cm3=\frac{Z\times 60.09 g/mol}{6.022\times 10^{23} mol^{-1}\times (0.700\times 10^{-7}cm)^{3}}$

$Z = 8$

1 silicon is 2 oxygen atoms. then 8 silicon atoms will be 16 oxygen atoms.

5 0

4 years ago

What SI unit would best be used to express the height of your classroom ceiling ?

chubhunter [2.5K]

Feet would be the best unit to use. Yards would work as well though.
Hope that helps!

7 0

3 years ago

Assume that an exhaled breath of air consists of 74.8% N2, 15.3% O2, 3.7% CO2, and 6.2% water vapour.

Goryan [66]

Answer:

a) PN₂ = 0.733 atm

PO₂ = 0.150 atm

PCO₂ = 0.036 atm

Pwater = 0.061 atm

b) 6.44x10⁻⁴ mol

c) 0.02 g

Explanation:

a) By the Dalton's Law, in a gas mixture, the total pressure is the sum of the partial pressures, and the partial pressure is the molar fraction of the gas multiplied by the total pressure.

PN₂ = 0.748*0.980 =0.733 atm

PO₂ = 0.153*0.980 = 0.150 atm

PCO₂ = 0.037*0.980 = 0.036 atm

Pwater = 0.062*0.980 = 0.061 atm

b) The number of moles of CO₂ can be calculated by the ideal gas law:

PV = nRT, where P is the pressure, V is the volume (0.455 L), n is the number of moles, R is the gas constant (0.082 atm.L/mol.K), and T is the temperature (37°C + 273 = 310 K).

0.036*0.455 = 0.082*310*n

25.42n = 0.01638

n = 6.44x10⁻⁴ mol

c) For the combustion reaction of glucose:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

So, the stoichiometry is:

1 mol of glucose ------- 6 moles of CO₂

x ------- 6.44x10⁻⁴ mol of CO₂

By a simple direct three rule:

6x = 6.44x10⁻⁴

x = 1.073x10⁻⁴mol of glucose

Glucose has a molar mass equal to 180 g/mol, and its mass is the molar mass multiplied by the number of moles:

m = 180x1.073x10⁻⁴

m = 0.02 g

8 0

3 years ago

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n200080 [17]

Answer:

- A ball does not move unlesss you kick it and it rolls aways

- a car stays still and is not in motion, unless you start the engine

- a pencil stays still on a table, it moves when you pick it up off the table

Explanation:

7 0

3 years ago