Answer:
20 m/s
Explanation:
Distance covered by man =500m
Time taken by man=25 seconds
Speed of man = distance/time
= 500/25
=20 m/s
Answer:
The rate of the reaction would increase.
Explanation:
The activation energy in chemistry and biology is the energy that a system needs before it can start a certain process. The activation energy is usually used to designate the minimum energy necessary for a given chemical reaction to occur. For a reaction to occur between two molecules, they must collide in the correct orientation and have a minimum amount of energy. As the molecules approach, their electron clouds repel. This requires energy (activation energy) and comes from the heat of the system, that is, the translational, vibrational energy of each molecule.
The activation energy of the reaction corresponds to the energy necessary for the reaction to be carried out with less reagent energy. The lower the activation energy of a reaction, the higher the speed of the reaction.
A reaction is called exothermic when it provides for the medium a higher energy than is necessary to reach the activated complex.
When a reaction is endothermic, it provides for the environment a lower energy than is necessary to reach the activated complex.
Catalysts are substances that decrease the activation energy for a given reaction, without altering its ΔH. The catalysts do not alter during the reactions.
Answer: No , a chemical change has not occured as it was easily reversed.
Explanation:
Chemical change is defined as a change in which rearrangement of atoms take place and leads to formation of new substances. It can only be reversed with the help of a chemical reaction.
Physical change is defined as a change which leads to change in shape, size or state of the substance changes. No new substance is formed.It can be easily reversed.
As the hair colour was washed out and returned to its original brown colour, it was a physical change.
Answer:
The amount of time needed for this heating to occur is 126.25 min
Explanation:
Given;
power required to heat the room = 2kW
volume of the room = 5 m X 5 m X 6 m = 150 m³
atmospheric pressure at sea level = 101 Kpa
Internal energy available in this room, E = PV
= 101 Kpa*150m³
= 15,150 Kpa.m³ = 15,150 KJ
P*t = E
where;
t is the time required to heat this room
1 kW = 3600 kJ/h
2 kW = 7200 kJ/h
Therefore, the amount of time needed for this heating to occur is 126.25 min
B. Transverse Wave this is the correct answer