Answer:
- <em><u>A physical change has occurred, with no energy change.</u></em>
Explanation:
When a pencil lead is broken there is not change of any chemical properties, therefore it is not a chemical change, but just a physical change. In this case the change is just the number of pieces and dimensions.
Chemical changes always involve the formation of new different substances; the bonds between the atoms of the starting substances (reactants) breake and new bonds are formed leading to new substances (products) with different chemical composition (arrange of atoms). Chemical changes occur through chemical reactions.
Hence, if there is not change on the chemical composition, you think on physical changes. Physical changes include change in shape, size, state of matter (e.g. solid, liquid, gas). In the case of a pencil lead breaking, it is a change in shape and size.
Also, since energy has not been absorbed or released during the change, the energy of the pencil lead before having been broken is equal to the sum of the energies of the pieces of pencil lead obtained. So, this is a physical change with no energy changes.
Some examples of physical changes that include change in energy are the change of state (e.g. solid to liquid or liquid to gas) and the dissolution of a compound.
Answer:
Easy 46 million turkeys
Medium three days
Hard: 1934
Fun: The first President on record issuing a "pardon" to his turkey was Ronald Reagan.
Explanation:
hop tis helped
Answer:
When a light is shone on the extract, pigment molecules absorb energy. Because the pigments have been isolated from the thylakoid membranes of the chloroplasts, the energy cannot be used for photosynthesis. Instead, the energy is released as heat and light in a process called fluorescence.
Answer:
120 liters
Explanation:
From the question,
Applying boyles law
PV = P'V'................ Equation 1
Where P = initial pressure, V = Initial Volume, P' = Final pressure, V' = Final Volume.
make V' The subject of the equation
V' = PV/P'............. Equation 2
Given: P = 2 kpa, V = 60 liters, P' = 1 kpa
Substitute these values into equation 2
V' = (2×60)/1
V' = 120 liters
Hence the right option is A. 120 liters