Answer:
6. 350kg
7. 800kg
8.600 meters
Explanation: I don’t like Stealing point but this is what I think I should give you and I don’t know how your teacher learn you this...
Answer:
The acceleration is: 
Explanation:
Given
--- The initial velocity
--- time
-- The final velocity
Required
Determine the acceleration
To do this, we make use of the first equation of motion

We used negative because the car was coming to stop.
This gives:


Collect like terms

Solve for a


<span><span>Convert the percentages into decimals (you can do that by dividing the percent by 100), then multiply that by its
corresponding mass to find its relative amount/ contribution to the
atomic mass of chromium. After doing so, add all of the obtained values
together to get the average mass.
</span>
83.79% = .08379
9.50% = .095
4.35% = .0435
2.36% = .0236
Average mass of chromium = 0.8379(51.94) + 0.095( 52.94) + 0.0435(49.95) + 0.0236(53.94)
Answer: 52amu
P.S. never forget units
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