Answer: a) 3.85 days
b) 10.54 days
Explanation:-
Expression for rate law for first order kinetics is given by:
where,
k = rate constant = ?
t = time taken for decomposition = 3 days
a = let initial amount of the reactant = 100 g
a - x = amount left after decay process = 
First we have to calculate the rate constant, we use the formula :
Now put all the given values in above equation, we get
a) Half-life of radon-222:
Thus half-life of radon-222 is 3.85 days.
b) Time taken for the sample to decay to 15% of its original amount:
where,
k = rate constant = 
t = time taken for decomposition = ?
a = let initial amount of the reactant = 100 g
a - x = amount left after decay process = 
Thus it will take 10.54 days for the sample to decay to 15% of its original amount.
Answer:
hey mate
answer is probably voltage as per me
as
Explanation:
Voltage, electric potential difference, electric pressure or electric tension is the difference in electric potential between two points, which is defined as the work needed per unit of charge to move a test charge between the two points
I would say D. because you round to the nearest whole number and 0.04 is way less than 0.5 which is a good rounding up number.
To solve the problem it is necessary to apply the concepts related to Force of Friction and Tension between the two bodies.
In this way,
The total mass of the cars would be,
Therefore the friction force at 29Km / h would be,
In this way the tension exerts between first car and locomotive is,
Therefore the tension in the coupling between the car and the locomotive is 
Answer:
14 seconds
Explanation:
Distance covered by sports car is measured with 21*t where t is time.
Distance covered by police is measured with at^2/2(t-time, a-acceleration) as it doesnt have starting velocity. If the distances are equal(police catches sport car)
then we have 21t=3/2*t^2 Solving this equation we get t=14 & t=0;
excluding the starting point we have 14 seconds
