Answer:
element
Explanation:
we know that helium is a pure substance although helium atoms are sometimes mixed with their isotopes it is still the same element. since there is no other element combined with helium this makes it an element.
Answer:
D) 65.7%
Explanation:
Based on the reaction:
2H2(g)+O2(g)⟶2H2O(l)
<em>2 moles of hydrogen produce 2 moles of water assuming an excess of oxygen.</em>
<em />
To find percent yield of the reaction we need to find theoretical yield (The yield assuming all hydrogen reacts producing water). With theoretical yield and actual yield (32.8g H₂O) we can determine percent yield as 100 times the ratio between actual yield and theoretical yield.
<em>Theoretical yield:</em>
Moles of 5.58g H₂:
5.58g H₂ ₓ (1 mol / 2.016g) = 2.768 moles H₂
As 2 moles of H₂ produce 2 moles of H₂O, if all hydrogen reacts will produce 2.768 moles H₂O. In grams:
2.768 moles H₂O ₓ (18.015g / mol) =
49.86g H₂O is theoretical yield
<em>Percent yield:</em>
Percent yield = Actual yield / Theoretical yield ₓ 100
32.8g H₂O / 49.86g ₓ 100 =
65.7% is percent yield of the reaction
<h3>D) 65.7%
</h3>
Answer:
Malachite
Explanation:
Malachite is the only listed compound that must contain copper and oxygen.
Copper and oxygen are both elements found on the periodic table. They have the following symbols;
Copper = Cu
Oxygen = O
From the given choices, only option 1 has the symbol Cu and O.
So only malachite contains both copper and oxygen.
Answer:
Explanation:
<em>2. A 10 kg bowling ball would require what force to accelerate down an alleyway at a rate of 3m/s² ?</em>
Notice that I completed the question with the garbled and missing values:
<u>Data:</u>
<u />
<u>Physical principles:</u>
- Newton's second law:
<u>Solution:</u>
<em></em>
<em>3. Salty has a car that accelerates at 5 m/s². If the car has a mass of 1000 kg, how much force does the car produce?</em>
Notice that I arranged the typos.
<u />
<u>Data:</u>
<u>Physical principles:</u>
- Newton's second law:
<u>Solution:</u>
<em>4. What is the mass of a falling rock if it produces a force of 147 N?</em>
<u>Data:</u>
<u>Physical principles:</u>
- neglecting air resistance ⇒ a = g: gravitational acceleration: 9.8m/s²
- Newton's second law:
<u>Solution:</u>
- Clear m from Newton's second law
- Substitute with F = 147 N and a = g = 9.8m/s², and compute
<em></em>
<em>5. What is the mass of a truck if it produces a force of 14,000 N while accelerating at a rate of 5 m/s²?</em>
<u>Data:</u>
<u>Physical principles:</u>
- Second Newton's law:
<u>Solution:</u>
- Clear m from Newton's second law
- Substitute with F = 14,000 N and a = 5m/s², and compute
Answer:
The nervous system
Explanation:
The nervous system send messages from the brain to the muscles to move.