Answer: 17 years
Explanation:
Expression for rate law for first order kinetics for radioactive substance is given by:

where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) for completion of half life:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.


b) for 8900 g of the mass of the sample to reach 7700 grams


Thus it will take 17 years
Answer:
The answer to this is
The velocity of the 27.3Kg marble after collision is = 16.24 cm/s
Explanation:
To solve the question, let us list out the given variables and their values
Mass of first marble m1 = 27.3g
Velocity of the first marble v1 = 21.0 cm/s
Mass of second marble m2 = 11.7g
Velocity of the second marble v2 = 12.6 cm/s
After collision va1 = unknown and va2 = 23.7 cm/s
From Newton's second law of motion, force = rate of change of momentum produced
Hence m1v1 + m2v2 = m1va1 + m2va2 or
va1 = (m1v1 + m2v2 - m2va2)÷m2 or (720. 72-277.29)÷m1 → va1 = 16.24 cm/s
The velocity of the 27.3Kg marble after collision is = 16.24 cm/s
Answer:
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Yo sup??
Heat produced per gram of reactant=13.1 KJ
.=13100 J
Actual heart produced=1850 J
By applying unitary method we get the weight of reactant to be x
x=1850/13100
=0.141 gm
Hope this helps