Answer:
4 half-lives will occur during this period of time.
Explanation:
Formula used :



where,
a = amount of reactant left after n-half lives and time t
= Initial amount of the reactant.
decay constant
= half life of an isotope
n = number of half lives
We have :

a = ?
t = 552 days





n = 4
4 half-lives will occur during this period of time.
Answer:
c.
=0 and 
Explanation:
We are given that two particles collide and stick together.
If there is no external force act on the two particles then ,it is inelastic collision.
Inelastic collision: There is some loss of kinetic energy but the momentum is conserved.
According to law of conservation of momentum
Initial momentum=Final momentum
Change in momentum=Final momentum-Initial momentum=0
Change in momentum=
Initial kinetic energy is greater than final kinetic energy.
Change in kinetic energy=Final kinetic energy-kinetic energy=- negative

Hence, option c is true.
c.
=0 and 
<span>
M = Au + Ag + Cu
Au = 75 *.28/16
Ag = 9*.28/16
Cu = 0.28
Add them all and you will get the answer.</span>
Answer:
By 1000 joules
Explanation:
Given


Required
By how much does her GPA increases
To do this, we simply calculate the potential energy.

Where

At the ground level, the height is 0
i.e. 
So:

At:

So, we have:



Calculate the difference


<em>Hence, it increases by 1000 joules</em>
Answer:
C
Explanation:
A wheel and axle, a lever, and a screw are all simple machines.
A pair of scissors is not a simple machine.
Answer is C.