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Juli2301 [7.4K]

2 years ago

14

Which statement accurately describes dark matter?

2 answers:

pickupchik [31]2 years ago

6 0

Yes it have to be C

Mandarinka [93]2 years ago

5 0

Answer:

C. It does not emit electromagnetic radiation.

Explanation:

Right now, Dark Matter is only a theory. Scientist proposed this to counter some of the strange phenomenon with matter in space.

Scientists know little about dark matter. Some say it's one of the driving forces of the universe. Currently, scientists have no way of measuring or identifying dark matter.

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Which of the following liquids would have the highest viscosity at room temperature?

Liono4ka [1.6K]

Answer:

5)HOCH2CH2OH

Explanation:

This is also known as ethylene glycol. An increase in hydrogen bonds of a compound means an increase in the viscosity. Hydrogen bonds occur as a result of bonding with electronegative elements such as Oxygen, Nitrogen etc.

The compounds with the highest amount of Hydrogen bond represents the one with the highest viscosity which is B) HOCH2CH2OH

3 0

2 years ago

When a aqueous solution of a certain acid is prepared, the acid is dissociated. Calculate the acid dissociation constant of the

stepan [7]

<h2> $K_a$ = $\dfrac{[H^{+}] [A^{-}]}{[HA]}$ </h2>

Explanation:

When an aqueous solution of a certain acid is prepared it is dissociated is as follows-

${\displaystyle {\ce {HA$ ⇄ ${H^+}+{A^{-}}} }}$

Here HA is a protonic acid such as acetic acid, $CH_3COOH$

The double arrow signifies that it is an equilibrium process, which means the dissociation and recombination of the acid occur simultaneously.

The acid dissociation constant can be given by -

$K_a$ = $\dfrac{[H^{+}] [A^{-}]}{[HA]}$

The reaction is can also be represented by Bronsted and lowry -

$\\{\displaystyle {\ce {{HA}+ H_2O}$ ⇄ $[H_3O^+] [A^-]$

Then the dissociation constant will be

$K_a$ = $\dfrac{[H_3O^{+}] [A^{-}]}{[HA]}$

Here, $K_a$ is the dissociation constant of an acid.

6 0

3 years ago

The solubility product of PbI2 is 7.9x10^-9. What is the molar solubility of PbI2 in distilled water?

Agata [3.3K]

<u>Answer:</u> The molar solubility of $PbI_2$ is $1.25\times 10^{-3}mol/L$

<u>Explanation:</u>

Solubility is defined as the maximum amount of solute that can be dissolved in a solvent at equilibrium.

Solubility product is defined as the product of concentration of ions present in a solution each raised to the power its stoichiometric ratio.

The balanced equilibrium reaction for the ionization of calcium fluoride follows:

$PbI_2\rightleftharpoons Pb^{2+}+2I^-$

s 2s

The expression for solubility constant for this reaction will be:

$K_{sp}=[Pb^{2+}][I^-]^2$

We are given:

$K_{sp}=7.9\times 10^{-9}$

Putting values in above equation, we get:

$7.9\times 10^{-9}=(s)\times (2s)^2\\\\7.9\times 10^{-9}=4s^3\\\\s=1.25\times 10^{-3}mol/L$

Hence, the molar solubility of $PbI_2$ is $1.25\times 10^{-3}mol/L$

3 0

2 years ago

Answer me fast!

Ede4ka [16]

Distance and time is needed for determining speed

8 0

2 years ago

Energy is released into the cell by

dsp73

Answer:

cellular respiration

Explanation:

4 0

2 years ago