Regents Review June 11

Regents Review June 11

By NAUDIA LAWRENCE

Significant figures review

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​Significant Figures Rules

1. All non zero numbers are significant (1,2,3 etc)

2. Leading zeros are never significant - even with a decimal.

3. Zeros between numbers are significant​

4. Trailing zeros are not signicant unless there is a decimal

5. If there is a decimal count all zeros that are not in front

Subject | Subject

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o.ooo234

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3040

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23400

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23400.0

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23400.0

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23400.010

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0.01020

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Multiple Choice

How many significant figures does the following number have: 0.002040

• 6

• 4

• 3

• 2

Multiple Choice

How many significant figures does the following number have: 0.998005

• 9

• 10

• 6

• 5

Multiple Choice

How many significant figures does the following number have: 100.00210

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Multiple Choice

How many significant figures does the following number have: 100.3

• 4

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• 2

Multiple Choice

How many significant figures does the following number have: 56.040

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Nuclear Chemistry - Half life calculations​

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You might be asked 1 of three things

1. ​ Total amountbof substance

2. the amount remaining after a certain time​

3. half life (# of them or amount of actual time)​

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Always draw it out

1. total amount

2. amount remaining

3. half life​

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Multiple Choice

A radioactive isotope has a half-life of 2.5 years. Which fraction of the original mass remains unchanged after 10. years?

• 1/2

• 1/4

• 1/8

• 1/16

Multiple Choice

What fraction of a Sr-90 sample remains unchanged after 87.3 years?

• 1/2

• 1/4

• 1/3

• 1/8

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Check Table N

Find number of half lives​

​

Multiple Choice

What is the total number of years that must pass before only 25.00 grams of an original 100.0-gram sample of C-14 remains unchanged?

• (1) 2865 y

• (2) 5730 y

• (3) 11 460 y

• (4) 17 190 y

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Find on Table N

Also use table N to find the decay mode (type of radiation)

Multiple Choice

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Multiple Choice

Which radioisotopes have the same decay mode and have half-lives greater than 1 hour?

• (1) Au-198 and N-16

• ((2) Ca-37 and Fe-53

• 3) I-131 and P-32

• (4) Tc-99 and U-233

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Multiple Choice

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​Balance top and bottom numbers

DONT FORGET TO CHANGE ELEMENT

ISOMERS REVEIW

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Multiple Choice

The isomers butane and methylpropane have

• (1) the same molecular formula and the same properties

• (2) the same molecular formula and different properties

• (3) different molecular formulas and the same properties

• (4) different molecular formulas and different properties

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