Atmospheric pressure decreases as the height of a surface above ground level increases. This is because, as the altitude increases:
•the number of air molecules decreases
•the weight of the air decreases
•there is less air above a surface
This is why aircraft that fly at high altitudes must be pressurised. If the air pressure is too low, humans cannot take in oxygen quickly enough to meet their bodies’ needs.
2H₂ + O₂ ---> 2H₂O
2 mol...............2 mol
2 mol H₂ ---- 2 mol H₂O
5 mol H₂ ---- X
X = 5 mol H₂O
Answer:
False
Explanation:
In an exothermic process, the reaction gives off heat, and not takes it in. If it takes it in from the surroundings, then it would be endothermic.
Answer:
1) Dispersion forces: It is a type of force which is present between atoms and molecules. It is a weakest intermolecular force that occurs between atoms. It is also called induced dipole-induced dipole attraction.
2. Dipole-dipole: It is a type of attractive force which is present between the negative end of one molecule with the positive end of another molecule. This type of attractive force occurs between polar molecules.
3) Hydrogen bond: It is a type of electromagnetic force which is present between hydrogen and high electronegative atoms such as nitrogen and oxygen etc.
Answer:
Electric engines have efficiencies of roughly 90% whilst combustion engines about 10% to 30%. This is because combustion engines emit much more heat, which is always energy that is not used as work, and thus increases inefficiency.
Explanation:
