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3 years ago

Which of the following represents a physical change?

Chemistry

2 answers:

julsineya [31]3 years ago

8 0

A. Phase changing. When phase changes nothing chemically changes about the substance, its still the same thing.

damaskus [11]3 years ago

3 0

I believe the best choice for you to pick will be option A)

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Materials move across a cell membrane in a process called _______.

maxonik [38]

Answer:

Diffusion

Explanation:

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3 years ago

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What particles in an atom are involved in nuclear reactions

VikaD [51]

Answer:

Explanation:

Electrons are the negatively charged particles of an atom that are involved in chemical reactions. They are located outside the nucleus of an atom

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3 years ago

Dolomite is a mixed carbonate of calcium and magnesium. Calcium and magnesium carbonates both decompose upon heating to produce

Setler79 [48]

Answer:

72.03 %

Explanation:

Total mass of dolomite = 9.66 g

Let the mass of Magnesium carbonate = x g

The mass of calcium carbonate = 9.66 - x g

Calculation of the moles of Magnesium carbonate as:-

Molar mass of Magnesium carbonate = 122.44 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{x\ g}{84.3139\ g/mol}=\frac{x}{84.3139}\ mol$

Calculation of the moles of calcium carbonate as:-

Molar mass of calcium carbonate = 100.0869 g/mol

Thus,

$Moles= \frac{9.66 - x\ g}{100.0869\ g/mol}=\frac{9.66 - x}{100.0869}\ mol$

According to the reaction shown below:-

$MgCO_3\rightarrow MgO+CO_2$

$CaCO_3\rightarrow CaO+CO_2$

In both the cases, the oxides formed from the carbonates in the 1:1 ratio.

So, Moles of MgO = $\frac{x}{84.3139}\ mol$

Molar mass of MgO = 40.3044 g/mol

Thus, Mass = Moles*Molar mass = $\frac{x}{84.3139}\times 40.3044 \ g$

Moles of CaO = $\frac{9.66 - x}{100.0869}\ mol$

Molar mass of CaO = 56.0774 g/mol

Thus, Mass = Moles*Molar mass = $\frac{9.66 - x}{100.0869}\times 56.0774 \ g$

Given that total mass of the oxide = 4.84 g

Thus,

$\frac{x}{84.3139}\times 40.3044 +\frac{9.66 - x}{100.0869}\times 56.0774=4.84$

$\frac{40.3044x}{84.3139}+56.0774\times \frac{-x+9.66}{100.0869}=4.84$

$-694.1618435x+45673.48749\dots =40843.38968\dots$

$x=\frac{4830.09780\dots }{694.1618435}$

$x=6.9582$

Thus, the mass of Magnesium carbonate = 6.9582 g

$\%\ mass=\frac{Mass_{MgCO_3}}{Total\ mass}\times 100$

$\%\ mass=\frac{6.9582}{9.66}\times 100=72.03\ \%$

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3 years ago

Billions of pounds of urea are produced annually for use as a fertilizer. Balance the skeletal equation for the synthesis of ure

klio [65]

2NH₃(g) + CO₂(g) → CO(NH₂)₂(s) + H₂O(l)
is the balanced equation for the synthesis of urea.

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3 years ago

¿Cuántos electrones conforman un enlace doble?

Aleks04 [339]

Answer:

Cada átomo aporta dos electrones al enlace, es decir, se comparten dos pares de electrones entre dos átomos. Un ejemplo es la molécula de Oxígeno (O2).

Explanation:

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3 years ago