Answer:
Mass of solution=100g
mass of salt=20g
so; mass of solute=80g
percentage composition =(mass of salt/total
mass) ×100
= \frac{20}{100} \times 100 \\ = 20\%
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Answer:
1. B, D,
2.A, F
Explanation:
1. According to the law of conservation of mass, In a course of chemical reaction, matter can neither be created nor destroyed but can be changed from one form to another. This means the amount of matter at the begining and ending of a reaction must be thesame.
2. Chemical reaction is not easily reversible. when gas is produced, provided the reaction system is an open system, the gas cannot be recovered and the reactants cannot be recovered from the products. likewise color change are attributed to chemical reaction
The answer is B. The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume.
Answer:
Order, sensitivity or response to the environment, reproduction, growth and development, regulation, homeostasis, and energy processing.
Answer:
There were originally 8 atoms of Potassium-40.
Explanation:
The half-life of a radioactive material is the time taken for half the original material to decay or the time required for a quantity of the radioactive substance to reduce to half of its initial value.
If the original material formed without any Argon-40, it means that the atoms originally present were Potassium-40 atoms.
Presently, there are 7 Argon-40 atoms for every 1 of Potassium-40, we can deduce the number of half-lifes the Potassium-40 has undergone as follows :
After one half-life, (1/2) there will be one Potassium-40 atom for every Argon-40 atom.
After a second half life, 1/2 × 1/2 = 1/4: there will be one Potassium-40 atom for every three atoms of Argon-40.
After a third half-life, 1/4 × 1/2 = 1/8: there will be one Potassium-40 atom for every 7 atoms of Argon-40.
Since there are 1/8 atoms of Potassium-40 presently, there were originally 8 atoms of Potassium-40.
