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Grace [21]
3 years ago
12

Which of the following is NOT a reason why index fossils are chosen for determining ages of rocks? Select all that apply.

Chemistry
1 answer:
Anarel [89]3 years ago
5 0

Answer:

Lol

Explanation:

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What are standards or attributes of a design that can be measured.
ankoles [38]

Explanation:

attribute of a person that often cannot be measured directly but can be assessed using numbers of indicators or manifest variables

4 0
3 years ago
In science, we like to develop explanations that we can use to predict the outcome of events and phenomena. Try to develop an ex
Kay [80]

The question is incomplete. The complete question is :

In science, we like to develop explanations that we can use to predict the outcome of events and phenomena. Try to develop an explanation that tells how much NaOH needs to be added to a beaker of HCl to cause the color to change. Your explanation can be something like: The color change will occur when [some amount] of NaOH is added because the color change occurs when [some condition]. The goal for your explanation is that it describes the outcome of this example, but can also be used to predict the outcome of other examples of this phenomenon. Here's an example explanation: The color of the solution will change when 40 ml of NaOH is added to a beaker of HCl because the color always changes when 40ml of base is added. Although this explanation works for this example, it probably won't work in examples where the flask contains a different amount of HCl, such as 30ml. Try to make an explanation that accurately predicts the outcome of other versions of this phenomenon.

Solution :

Consider the equation of the reaction between NaOH and $HCl$

  NaOH (aq) + HCl (aq) → NaCl(aq) + $H_2O (l)$

The above equation tells us that $1 \text{mole}$ of $NaOH$ reacts with $1 \text{mole}$ of $HCl$.

So at the equivalence point, the moles of NaOH added = moles of $HCl$present.

If the volume of the $HCl$ taken = $V_1$ mL and the conc. of $HCl$ = $M_1$  mole/L

The volume of NaOH added up to the color change = $V_2 \text{  and conc of NaOH = M}_2$ mole/L

Moles of $HCl$ taken = $V_1 \ mL \times M_1 \ mol/100 \ mL = V_2M_2 \times 10^{-3}$  moles.

The color change will occur when the moles of NaOH added is equal to the moles of $HCl$ taken.

Thus when $V_1 M_1 \times 10^{-3} = V_2M_2 \times 10^{-3}$

or   when    $V_1M_1 = V_2M_2$

or $V_2=\frac{V_1M_1}{M_2}$  mL of NaOH added, we observe the color change.

Where $V_1, M_1$ are the volume and molarity of the $HCl$ taken.

$M_2$ is the molarity of NaOH added.

When both the NaOH and $HCl$ are of the same concentrations, i.e. if $M_1=M_2$, then $V_2=V_1$

Or the 40 mL of $HCl$ will need 40 mL of NaOH for a color change and

30 mL of $HCl$ would need 30 mL of NaOH for the color change (provided the concentration $M_1=M_2$)

7 0
2 years ago
Pure metals tend to be weaker and more reactive than an alloy which is a
Alex17521 [72]
Alloys are supposed to give greater strength to metals, which is why gold is mixed with others to make it harder. They have greater strength and are more resistant to erosion.
5 0
3 years ago
A substance has a boiling point of 78 °C. Which of the following is true about the substance? (5 points) a It will also change f
vovangra [49]

Answer: If a substance has a boiling point of 78^{o}C then it is true that it will also change from a gas to a liquid at 78 °C while the gas loses energy.

Explanation:

The temperature at which vapor pressure of a liquid substance becomes equal to the atmospheric pressure is called boiling point of substance.

At the boiling point, liquid phase and vapor phase remains in equilibrium.

This means that as liquid phase changes into vapor phase and also vapor phase changes into liquid phase at the boiling point.

Thus, we can conclude that if a substance has a boiling point of 78^{o}C then it is true that it will also change from a gas to a liquid at 78 °C while the gas loses energy.

6 0
2 years ago
What is the formula of sulfurous acid?<br> H2S<br> HSO4<br> H2SO4<br> H2SO3
Bas_tet [7]

The correct answer is H2SO3 I took the assignment already


6 0
3 years ago
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