Answer:
147,558,601 sqkm
Explanation:
The earth is spherical in shape;
area of sphere = 4πr²
if 70.8% is covered by water then 100-70.8 will be land,
= 29.2%
area occupied by land = (29.2/100) * 4πr²
= 0.292*4*3.142*(6371)²
=147,558,601 sqkm
Answer:
126.4 g of 
are required
Explanation:
Balanced reaction: 
According to balanced reaction-
8 moles of 
are produced from 2 moles of
So, 8.70 moles of are produced from 
moles of or 2.175 moles of
Molar mass of = 58.12 g/mol
So, mass of required = 
= 126.4 g
Hence 126.4 g of are required
Answer:
The top number is the total mass number, particles in an atom of an element that have mass are protons and neutrons.
Explanation:
Answer:
The correct option is;
D)
Explanation:
The given reaction is presented as follows;
NH₄Cl (s) → NH₃ (g) + HCl (g) ΔH° = 176 kJ/mol, ΔS° = 0.285 kJ/(mol·K)
We note that the Gibbs free energy, ΔG° is represented by the following equation;
ΔG° = ΔH° - T·ΔS°
Where:
T = Temperature (Kelvin)
The reaction will be spontaneous for exergonic reactions, ΔG° < 0 and it will not be spontaneous for endergonic reaction, ΔG° > 0
At room temperature, T = 25 + 273.15 = 298.15 K
Which gives;
ΔG° = 176 - 298.15 × 0.285 = 91.03 kJ/mol which is > 0 Not spontaneous reaction
At 800°C, we have;
T = 273.15 + 800°C + 1073.15 K
ΔG° = 176 - 1073.15 * 0.285 = -129.85 kJ/mol which is < 0 the reaction will be spontaneous
The correct option is therefore, that at room temperature, the reaction is not spontaneous. However, at high temperatures. like 800 °C, the free energy value turns negative and this reaction becomes spontaneous.
