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Alex787 [66]
3 years ago
8

In the past, agriculture work was completed by

Chemistry
2 answers:
Alecsey [184]3 years ago
4 0
Farmers?!

Agricultural work was always done by the farmers, no matter what time period it was!
Nimfa-mama [501]3 years ago
3 0

human and animals.................


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Why don’t the common ions in humans (na+, k+, cl-, etc.) cluster together in cells?
mariarad [96]
The answer is because like electric charges do not attract with each other. Ions either lack or have excess electrons in their atomic structure. Ions with a positive charge are called cations. They lack electrons in their atoms so they have to pair up with negatively charged ions, called anions, because they have excess electrons. Together, they form a compound that is neutral.
7 0
3 years ago
Define the term ligand. Cu2+(aq) reacts with ammonia to form the complex ion
photoshop1234 [79]
The answer is ligand: a molecule or ion that can bond to a (central) metal ion (to form a complex);
NH3: Lewis base and Cu2+: Lewis acid (need both for mark);
<span>each NH3/ligand donates an electron pair (to Cu2+); forming coordinate covalent/dative covalent bond; i hope this help you.</span>
4 0
3 years ago
How do I describe an ion?
worty [1.4K]

Answer:

Explanation:

How do I describe an ion?

<h2>an ion is an atom that has had electrons added or taken away from it.</h2><h2>they do this in order to obtain a stable electronic configuration like their closest noble gas..see Periodic Table column 18 which is also column VIIIA</h2><h2>If they gain electrons, they are negative and are called</h2><h2>ANIONS</h2><h2>if they lose  electrons they are positive and are called</h2><h2>CATIONS  </h2><h2 />

5 0
3 years ago
PLEASE HELPPP!!!!
aksik [14]

Answer:

b. 11.90 Liters

Explanation:

  • The balanced equation for the mentioned reaction is:

<em>3O₂ + 4Al → 2Al₂O₃,</em>

It is clear that 3.0 moles of O₂ react with 4.0 moles of Al to produce 2.0 Al₂O₃.

  • Firstly, we need to calculate the no. of moles (n) of 36.12 g of Al₂O₃:

<em>n = mass/molar mass</em> = (44.18 g)/(101.96 g/mol) = <em>0.4333 mol.</em>

<u><em>using cross multiplication:</em></u>

3.0 mol of O₂ produces → 2.0 mol of Al₂O₃.

??? mol of O₂ produces → 0.4333 mol of Al₂O₃.

<em>∴ The no. of moles of O₂ needed to produce 36.12 grams of Al₂O₃</em> = (3.0 mol)(0.4333 mol)/(2.0 mol) = <em>0.65 mol.</em>

  • Now, we can find the volume of O₂ used during the experiment:

We can use the general law of ideal gas: <em>PV = nRT.</em>

where, P is the pressure of the gas in atm (P = 1.3 atm).

V is the volume of the gas in L (V = ??? L).

n is the no. of moles of the gas in mol (n = 0.65 mol).

R is the general gas constant (R = 0.0821 L.atm/mol.K),

T is the temperature of the gas in K (T = 290 K).

<em>∴ V = nRT/P </em>= (0.65 mol)(0.0821 L.atm/mol.K)(290 K)/(1.3 atm) = <em>11.9 L.</em>

<em>So, the right choice is: b. 11.90 Liters.</em>

8 0
4 years ago
What is the heat required to vaporize 650 grams of a liquid with a heat of vaporization of 723 joules/grams?
wolverine [178]

Your answer would be E. 470,000 J

3 0
4 years ago
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