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Lostsunrise [7]

2 years ago

8

A book on a table presses downward with a force equal to the upward force exerted by the table. This is an example of Newton's__

____ law of motion.
A.SECOND
B.FIRST
C.THIRD

2 answers:

Vsevolod [243]2 years ago

4 0

A
Is the correct answer

Lerok [7]2 years ago

3 0

Answer:

a

Explanation:

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The reaction of sodium peroxide and water produces sodium hydroxide and oxygen gas. The following balanced chemical equation rep

a_sh-v [17]

Answer:

3.925 mol.

Explanation:

From the balanced equation:

<em>2 Na₂O₂(s) + 2 H₂O(l) → 4 NaOH(s) + O₂(g) ,</em>

It is clear that 2 moles of Na₂O₂ react with 2 moles of H₂O to produce 4 moles of NaOH and 1 mole of O₂ .

<em>Using cross multiplication:</em>

4 moles of NaOH produced with → 1 mole of O₂ .

15.7 moles of NaOH produced with → ??? mole of O₂ .

<em>∴ The no. of moles of O₂ made =</em> (1 mole)(15.7 mole)/(4 mole) = <em>3.925 mol.</em>

8 0

3 years ago

The ka values for several weak acids are given below. which acid (and its conjugate base) would be the best buffer at ph = 8.0?

Pie

One of the best buffer choice for pH = 8.0 is Tris with Ka value of 6.3 x 10^-9.

To support this answer, we first calculate for the pKa value as the negative logarithm of the Ka value:
pKa = -log Ka

For Tris, which is an abbreviation for 2-Amino-2-hydroxymethyl-propane-1,3 -diol and has a Ka value of 6.3 x 10^-9, the pKa is
pKa = -log Ka
= -log (6.3x10^-9)
= 8.2

We know that buffers work best when pH is equal to pKa:
pKa = 8.2 = pH

Therefore Tris would be a best buffer at pH = 8.0.

7 0

3 years ago

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Chemical formula for 2 butyene is <br>

yarga [219]

Answer:

$\text{C}_4\text{H}_6$

Explanation:

3 0

2 years ago

What type of flower is this? This is for a science project.

kenny6666 [7]

I believe that is a plant called Wisteria.

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2 years ago

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what volume of a 0.155 M calcium hydroxide solution is required to neutralize 28.8 mL of a 0.106 M nitric acid?

Hitman42 [59]

Answer:

9.85mL

Explanation:

First, let us write a balanced equation for the reaction. This is illustrated below:

Ca(OH)2 + 2HNO3 —> Ca(NO3)2 + 2H2O

From the balanced equation above,

nA (mole of the acid) = 2

nB (mole of the base) = 1

Data obtained from the question include:

Vb (volume of the base) =?

Mb (Molarity of base) = 0.155 M

Va (volume of the acid) = 28.8 mL

Ma (Molarity of acid) = 0.106 M

Using MaVa/MbVb = nA/nB, the volume of calcium hydroxide (i.e the base) can be obtain as follow:

MaVa/MbVb = nA/nB

0.106 x 28.8 / 0.155 x Vb = 2/1

Cross multiply to express in linear form as shown below:

2 x 0.155 x Vb = 0.106 x 28.8

Divide both side by 2 x 0.155

Vb = (0.106 x 28.8) / (2 x 0.155)

Vb = 9.85mL

Therefore, the Volume of calcium hydroxide is 9.85mL

7 0

2 years ago