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3 years ago

15

Which of the following best describes a physical change?*

2 answers:

Dennis_Churaev [7]3 years ago

5 0

Answer:

D

Explanation:

i had this question and i got it right

KATRIN_1 [288]3 years ago

4 0

Answer:

d

Explanation:

I took this test way back

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What is the pOH of a<br> 2.6 x 10-6 M H+ solution?

melomori [17]

Answer:

Approximately $8.41$ (assuming that the solution is at $\rm 25^\circ C$ , under which $K_{\rm w} = 10^{-14}$ .)

Explanation:

Let ${\rm [H^{+}]}$ and ${\rm [OH^{-}]}$ denote the concentration of $\rm H^{+}$ and $\rm OH^{-}$ respectively.

Let $K_{\rm w}$ denote the self-ionization constant of water. The exact value of $K_{\rm w}\!$ depends on the temperature of the solution. $K_{\rm w} =10^{-14}$ at $\rm 25^\circ C$ .

The product of ${\rm [H^{+}]}$ and ${\rm [OH^{-}]}$ in a solution (with $\rm M$ , or moles per liter, as the unit) is supposed to be equal to the $K_{\rm w}$ value of that solution at the corresponding temperature. In other words:

${\rm [H^{+}]} \cdot {\rm [OH^{-}]} = K_{\rm w}$ .

Rearrange to obtain an expression for ${[\rm OH^{-}]}$ :

$\begin{aligned}{\rm [OH^{-}]} &= \frac{K_{\rm w}}{[\rm H^{+}]}\end{aligned}$ .

Assume that the solution in this question is at $\rm 25^\circ C$ (for which $K_{\rm w} =10^{-14}$ .) For this solution:

$\begin{aligned}{\rm [OH^{-}]} &= \frac{K_{\rm w}}{[\rm H^{+}]} \\ &= \frac{10^{-14}}{2.6 \times 10^{-6}}\approx 3.85\times 10^{-9}\; \rm M\end{aligned}$ .

Hence, the $\rm pOH$ of this solution would be:

$\begin{aligned}\rm pOH &= -\log_{10}{\rm [OH^{-}]} \\&\approx -\log_{10} (3.85 \times 10^{-9}) \approx 8.41 \end{aligned}$ .

3 0

3 years ago

What solid can be formed from a net diagram that has 2 congruent circles and 1 rectangle?

Serggg [28]

Answer: Option (B) is the correct answer.

Explanation:

When two circles are of same same then they are known as congruent circles.

Whereas a rectangle is a kind of parallelogram with all sides equal to $90^{o}$ .

Therefore, when 2 congruent circles and 1 rectangle combines then it results in the formation of a cylinder.

Thus, we can conclude that solid formed when 2 congruent circles and 1 rectangle combines will be a circle.

5 0

3 years ago

Read 2 more answers

What volume of nitrogen (n2) would be completely consumed in the reaction with 30.80 g of

Shtirlitz [24]

The answer is 285.33g nitrogen would be completely consumed in the reaction with 30.80 g of hydrogen gas.

<h3>What is a mole ?</h3>

A mole is defined as 6.02214076 × 10²³ atoms, molecules, ions, or other chemical units.

Write a balanced equation.

Calculate the moles of H₂ in 30.8 g.

Calculate the moles of N₂ required to react with H₂.

Calculate the mass of N₂.

Calculate the initial mass of N₂.

Start with a balanced equation.

N₂ + 3H₂ --> 2NH₃

Calculate the moles of H₂ in 30.8 g.

n = m/M; where n = moles, m = mass, and M = molar mass.

M(H₂) = 1.008 g/mol

n(H₂) = (30.8 g)/(1.008 g/mol) = 30.56 mol H₂

Calculate the moles of N₂ required to react with 30.56 mol H₂ , using the mole ratio between H₂ and N₂ in the balanced equation.

30.56 mol H₂ × 1 mol N₂/3 mol H₂ = 10.18 mol N₂

Calculate the mass of N₂ in 10.18 mol.

m = n × M

M(N₂) = 2 × 14.007 g/mol N = 28.014 g/mol N₂

m(N₂) = 10.18 mol × 28.014 g/mol = 285.33g N₂

Therefore 285.33g nitrogen would be completely consumed in the reaction with 30.80 g of hydrogen gas.

To know more about mole

brainly.com/question/26416088

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5 0

2 years ago

Biochemical reactions in your cells occur best at approximately which temperature

timama [110]

Answer:

38°c

Explanation:

Biochemical reactions takes place in our body at an approximate temprature of 38°c...

4 0

3 years ago

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Question 1(Multiple Choice Worth 50 points)

irinina [24]

Answer:

because it's shellfish

Explanation:

A slipper

7 0

3 years ago

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