140 g of nitrogen (N₂)
Explanation:
We have the following chemical equation:
N₂ + 3 H₂ -- > 2 NH₃
Now, to find the number of moles of ammonia we use the Avogadro's number:
if 1 mole of ammonia contains 6.022 × 10²³ molecules
then X moles of ammonia contains 6.022 × 10²⁴ molecules
X = (1 × 6.022 × 10²⁴) / 6.022 × 10²³
X = 10 moles of ammonia
Taking in account the chemical reaction we devise the following reasoning:
If 1 mole of nitrogen produces 2 moles of ammonia
then Y moles of nitrogen produces 10 moles of ammonia
Y = (1 × 10) / 2
Y = 5 moles of nitrogen
number of moles = mass / molecular weight
mass = number of moles × molecular weight
mass of nitrogen (N₂) = 5 × 28 = 140 g
Learn more about:
Avogadro's number
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4 moles of NaCl is produced from 2 moles of Na₂CrO₄.
<u>Explanation:</u>
Given reaction is
PbCl₂(aq) + Na₂CrO₄(aq)→ PbCrO₄(s) + 2 NaCl (aq)
It is the balanced equation which means that on both sides of the equation, number of atoms of each element are equal.
From the above balanced equation it says that molar ratio of Na₂CrO₄ to NaCl is 1 : 2.
That is 1 mole of Na₂CrO₄ produces 2 moles of NaCl, so the molar ratio is 1:2.
2 moles of Na₂CrO₄ produces 4 moles of NaCl.
So the molar ratio of Na₂CrO₄ to NaCl is 2: 4.
Answer: A persistent or non-volatile chemical agent can remain on a surface for more than 24 hours.
Explanation:
Non-volatile substance is defined as the one which does not readily evaporate into its surrounding. Generally, a non-volatile substance has strong intermolecular forces between its molecules.
A non-volatile substance will take more than 24 hours to remain on the surface.
On the other hand, a substance with weak intermolecular forces present in its molecules will readily evaporate into the atmosphere.
For example, acetic acid is a volatile substance and quickly evaporates into the atmosphere.
Thus, we can conclude that a persistent or non-volatile chemical agent can remain on a surface for more than 24 hours.
Answer:
The correct option is: provide a source of counterions to prevent the build-up of charge at both the cathode to the anode.
Explanation:
A salt bridge is a U-shaped glass tube that is used in a voltaic cell or galvanic cell to connect the oxidation and reduction half-cells and complete the electric circuit.
<em>It allows the ions to pass through it, thus preventing the accumulation of charge on the anode and cathode as the chemical reaction proceeds.</em>
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Therefore, the correct option is: <u>provide a source of counterions to prevent the build-up of charge at both the cathode to the anode.</u>
