Explanation:
For the first part,
Reaction equation:
N₂ + 3H₂ → 2NH₃
Given:
Number of moles of NH₃ = 6 moles
Unknown:
Number of moles of N₂ = ?
Solution:
N₂ + 3H₂ → 2NH₃;
From the reaction above, we solve from the known specie to the unknown. Ensure that the equation is balanced;
2 moles of NH₃ is produced from 1 mole of N₂
6 moles of NH₃ will be produced from 
mole of N₂
= 3moles of N₂
The number of moles of N₂ is 3 moles
ii.
Given parameters:
Number of moles of sulfur = 2.4moles
Molar mass of sulfur = 32.07g/mol
Unknown:
Mass of sulfur = ?
Solution:
The number of moles of any substance can be found using the expression below;
Number of moles = 
Mass of sulfur = number of moles of sulfur x molar mass
Insert the parameters and solve;
Mass of sulfur = 2.4 x 32.07 = 76.97g
Tarnish is Ag2S-silver sulfide and the oxidation state of silver is +1
A local community needs to provide more electricity for its growing population. Currently, the community's electricity needs are met by coal-burning power plants several kilometres away. Citizens are concerned that burning more coal will produce too much air pollution.
Which of the following could be used as an alternative energy resource to help minimise air pollution in this community?
A. hydroelectric energy
B. solar energy
C. wind energy
<u>D. all of these
</u>
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The answer is C as it slowly destroys the ozone layer
The kinetic energy and the physical state of water depend strongly on the temperature;
- Firstly, The kinetic energy of water on a hot stove is higher than that on the counter in the freezer; that the kinetic energy is directly proportional to the temperature according to the relation:
; where R is the universal gas constant, T is the temperature and NA is Avogadro number.
As the temperature increases, the speed of colliding molecules increases and the kinetic energy increases.
- Secondly, The physical state of water depends on the temperature; water has three states (gas, liquid and solid) depends on the temperature.
- If a glass of water is putt on the counter in the freezer, it will be converted to the solid state (ice).
- And, as if it is putt on a hot stove, it will be vapor (gaseous state).
