The correct answer for this question would be option B. The common name of the group whose members are characterized by endoskeleton and a unique water vascular system are called the <span> Echinoderms. Examples of echinoderms are starfish, sea urchin, feather stars and sea cucumbers. Hope this is the answer that you are looking for.</span>
Answer:
The total pressure is 0,804 atm
Explanation:
We use Dalton's law according to which the sum of the partial pressures is equal to the total pressure of a gas mixture. We convert the pressure in Pascals to atmosphere (it can also be done in reverse):
101300Pa ----1 atm
4500Pa----x= (4500Pa x 1atm)/101300Pa= 0,044 atm
P total= p1 + p2= 0,76 atm + 0,044 atm=0,804 atm
The water reaches its boiling point and turns into water vapor. This process is a physical change. The change is substance status. And the physical change will not destroy the molecular structure. So the molecular structure will not change.
These are two questions and two answers.
1) Question: Which of the following pairs of reactants will react together to produce water (H2O) as one of the products?
<span>Fe(OH)₃ and CuO
Cu(OH)₂ and H₂S
MgO and Ca(OH)₂
SO₃ and H₂O
</span>
<span>Answer:
</span>
<span>Cu(OH)₂ and H₂S
</span>
Justification:
1) Fe(OH)₃ and CuO: to form water Cu and Fe should react with each other. Being them two metals, they will not do that. So this reaction is not possible.
2) Cu(OH)₂ and H₂S: Being S a non metal and Cu a metal, they can react to form a the salt CuS, and water, as per this equation:
<span>Cu(OH)₂ + H₂S → CuS + 2H₂O
</span>
<span>
3) MgO and Ca(OH)₂: Being Mg and Ca two metals they will not react with each other, so this reaction is not feasible.
</span>
<span>4) SO₃ and H₂O: this is an acid oxide and water reaction which yields to an acid, as per this equation:
</span>
<span>SO₃ + H₂O → H₂SO₄
</span>
Which is not producing water
<span>2) Question: Based on reactivity, which of the following elements can replace
aluminum (Al) in a compound during a single replacement reaction?
B
Ca
Zn
Fe
</span>
Answer: Ca.
Justification:
Only an element more reactive than Al will replace it <span>in a compound during a single replacement reaction.</span>
You may predict that being Ca an alkalyne earth element it is more reactive than Al and so Ca will replace Al.
Else, you have to search a reactivity table, where you will find this order of reactivity among the metals:
Ca more reactive than Al
Al more reactive than Zn
Zn more reactive than Fe.
<span />
Being B a metalloid, its matallic character is low and it is less reactive than the other metals on the list.
Answer:
1. observations
2. hypothesis
3. experimentation
Explanation:
Observations are made, Hypothesies are formed from observations, and experimnets help alter and comfirm hypothesis.
