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3 years ago

A certain atom has a number if four. How many protons does it have

Chemistry

2 answers:

liraira [26]3 years ago

6 0

The answer is 4 because
If Z = 4 then the atom is beryllium

user100 [1]3 years ago

3 0

4 protons are there in the atom

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Which statement accurately describes the origin and expansion of the universe? As the universe continues to expand, it gradually

dimulka [17.4K]

The answer is; Cosmic background radiation is leftover thermal energy from the big bang.

Called the coming microwave background the weak radiation fills the universe more or less uniformly. This radiation is the fossil remnants of the postulated big band at the beginning of the universe. The photos produced at the time continue to travel through the universe growing fainter over time and have fallen in the microwave range of the electromagnetic spectrum now.

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3 years ago

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Eddi Din [679]

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3 years ago

Calculate the solubility of carbon dioxide at 400 kPa.

BaLLatris [955]

The solubility of carbon dioxide at 400 kPa at room temperature is ;

( B ) 0.61 CO2/L

<u>Given data </u>

pressure of CO₂ = 400 Kpa = 3.95 atm

Kh of CO₂ = 3.3 * 10⁻² mol/L.atm

<h3>Calculate the solubility of carbon dioxide </h3>

Solubility = pressure * Kh value of CO₂

= 3.95 atm * 3.3 * 10⁻² mol / L.atm

= 0.13 mol/l CO₂

= 0.61 CO₂ / L

Hence we can conclude that the solubility of CO₂ at 400 kPa is 0.13 mol/l CO₂.

Learn more about solubility : brainly.com/question/23946616

From the options the closest answer is ( B ) 0.61 CO₂ / L

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2 years ago

To a 25.00 mL volumetric flask, a lab technician adds a 0.150 g sample of a weak monoprotic acid, HA , and dilutes to the mark w

Elis [28]

<u>Answer:</u> The number of moles of weak acid is $4.24\times 10^{-3}$ moles.

<u>Explanation:</u>

To calculate the moles of KOH, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}\text{Volume of solution (in L)}}$

We are given:

Volume of solution = 43.81 mL = 0.04381 L (Conversion factor: 1L = 1000 mL)

Molarity of the solution = 0.0969 moles/ L

Putting values in above equation, we get:

$0.0969mol/L=\frac{\text{Moles of KOH}}{0.04381}\\\\\text{Moles of KOH}=4.24\times 10^{-3}mol$

The chemical reaction of weak monoprotic acid and KOH follows the equation:

$HA+KOH\rightarrow KA+H_2O$

By Stoichiometry of the reaction:

1 mole of KOH reacts with 1 mole of weak monoprotic acid.

So, $4.24\times 10^{-3}mol$ of KOH will react with = $\frac{1}{1}\times 4.24\times 10^{-3}=4.24\times 10^{-3}mol$ of weak monoprotic acid.

Hence, the number of moles of weak acid is $4.24\times 10^{-3}$ moles.

6 0

3 years ago

25. How many ml of a .0023M strontium hydroxide solution are needed to completely react 15.0 mL of 0.012M hydrochloric acid?

Mariana [72]

Answer: There are 78.26 mL of a 0.0023M strontium hydroxide solution are needed to completely react 15.0 mL of 0.012M hydrochloric acid.

Explanation:

Given: $M_{1}$ = 0.0023 M, $V_{1}$ = ?

$V_{2}$ = 15.0 mL, $M_{2}$ = 0.012 M

Formula used to calculate volume of strontium hydroxide solution is as follows.

$M_{1}V_{1} = M_{2}V_{2}$

Substitute the values into above formula as follows.

$M_{1}V_{1} = M_{2}V_{2}\\0.0023 M \times V_{1} = 0.012 M \times 15.0 mL\\V_{1} = 78.26 mL$

Thus, we can conclude that there are 78.26 mL of a 0.0023M strontium hydroxide solution are needed to completely react 15.0 mL of 0.012M hydrochloric acid.

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3 years ago