Explanation:
A physical change is one that alters the physical properties of matter (particularly the form and state).
A chemical change is one in which new kind of matter is formed. It is always accompanied by energy changes (evolution or absorption of energy in form of heat or light or both).
Now, the salient differences between physical and chemical changes;
- Physical changes are easily reversible whereas chemical changes are not easily reversible.
- Physical changes lead to the production of no new kinds of matter whereas chemical changes leads to the production of new kinds of matter.
- Physical changes involves no change in mass whereas chemical changes involves change in mass.
- Physical changes require little energy whereas considerable amount of energy is needed for chemical changes.
Answer:
Explanation:
R = Rydberg constant = 
= Principal quantum number of an energy level = 2
= Principal quantum number of an energy level for the atomic electron transition = 4
Wavelength is given by the Rydberg formula
The wavelength of the light emitted is .
Answer:
Percent yield = 90.8%
Explanation:
The reaction of Fe with S to produce FeS is:
Fe + S → FeS
<em>Where the moles of Fe added in excess of S are the moles of FeS</em>
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Now, percent yield is defined as 100 times the ratio between actual yield (13.8g of FeS) and theoretical yield (15.2g FeS):
Percent yield = 13.8g / 15.2g * 100
<h3>Percent yield = 90.8%</h3>
Total change in energy = Heat produced by system + work done on the system
= 228 - 55
= 173 kJ
Because this energy is released as heat, the reaction is exothermic.
8) The gravitational force is a force of attraction between two objects. It can be expressed mathematically as:
F = G m₁*m₂/d² ------(1)
m₁ and m₂ are the masses of two interacting systems
d = distance between them
G = gravitational constant
Thus according to equation(1), the gravitational force is directly proportional to the mass of the objects. Greater the masses, stronger will be the force of attraction.
In this case, the distance (d) and the one of the masses i.e. mass of earth would be the same for both situations. However, since an elephant would weigh more than a human, the gravitational force will be stronger between an elephant and earth.
9) Since the masses of spheres is the same, the gravitational force between the red and blue spheres would be the same as well, provided the distance d remains constant.
