The rate constant of the reaction K we can get it from this formula:
K=㏑2/ t1/2 and when we have this given (missing in question):
that we have one jar is labeled t = 0 S and has 16 yellow spheres inside and the jar beside it labeled t= 10 and has 8 yellow spheres and 8 blue spheres and the yellow spheres represent the reactants A and the blue represent the products B
So when after 10 s and we were having 16 yellow spheres as reactants and becomes 8 yellow and 8 blue spheres as products so it decays to the half amount so we can consider T1/2 = 10 s
a) by substitution in K formula:
∴ K = ㏑2 / 10 = 0.069
The amount of A (the reactants) after N half lives = Ao / 2^n
b) so no.of yellow spheres after 20 s (2 half-lives) = 16/2^2 = 4
and the blue spheres = Ao - no.of yellow spheres left = 16 - 4 = 12
c) The no.of yellow spheres after 30 s (3 half-lives) = 16/2^3 = 2
and the blue spheres = 16 - 2 = 14
Half-life is the time taken for the concentration of the substance to reduce by 50%. The original sample of strontium had a mass of 1.6 gms. Thus, option d is correct.
<h3>What is half-life?</h3>
The half-life of any radioactive substance is the time period at which the concentration will get reduced to half the initial amount. The initial mass of Sr-90 is calculated as,
Given,
Quantity of the remaining substance N (t) = 0.40 gm
Initial radioactive substance quantity 
=?
Time duration (t) = 56 years
Half-life = 28 years
Substituting values above:
= 1.6 gm
Therefore, option d. the initial mass of Sr is 1.6 gm.
Learn more about half-life here:
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Answer:
1)clinical thermometer has temperature range 35 to 42degree celcius where labouratery thermometer has -10 to 110 degree celcius.
2)clinical thermometer is used to measure body temperature whare labouratory thermometer is not used to measure body temperature
Answer:
C
Explanation:
The Law of Conservation of Mass states that matter cannot be created or destroyed and must be conserved. I is stating matter cannot be created, which is true. II is saying that matter can only be rearranged/conserved, which again is true. III states matter cannot be destroyed, which is also true. IV is incorrect because it doesn't make sense. Matter does matter.
