Answer:
a. 0.66 atm
Explanation:
Pi = 750 torr = 0.99 atm. Pf = ?
Vi = 400 ml Vf = 600ml
Using PiVi = PfVf
Then 400ml × 0.99atm = Pfatm × 600ml
Solving for Pf, we have,
Pf = (400ml × 0.99atm)/600ml
Pf = 0.66atm
<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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2KClO3 --> 2KClO2 + O2
12 6 (moles)
The ratio of KClO3 and O2 is 2:1. This means 2 moles of KClO3 can create 1 mole of O2. So 12 moles of KClO3 will create 6 moles of O2.
Percent error (%)= 
Accepted value is true value.
Measured values is calculated value.
In the question given Accepted value (true value) = 63.2 cm
Given Measured(calculated values) = 63.1 cm , 63.0 cm , 63.7 cm
1) Percent error (%) for first measurement.
Accepted value (true value) = 63.2 cm, Measured(calculated values) = 63.1 cm
Percent error (%)= 



Percent error = 0.158 %
2) Percent error (%) for second measurement.
Accepted value (true value) = 63.2 cm, Measured(calculated values) = 63.0 cm
Percent error (%)= 



Percent error = 0.316 %
3) Percent error (%) for third measurement.
Accepted value (true value) = 63.2 cm, Measured(calculated values) = 63.7 cm
Percent error (%)= 




Percent error = 0.791 %
Percent error for each measurement is :
63.1 cm = 0.158%
63.0 cm = 0.316%
63.7 cm = 0.791%