How to solve these Chemistry problems?

Question

These are the problems, and their multi-choice answers.

1. Which value is closest to the amount of gasoline in a small car with a full tank (which contains about 13 gallons)?

A. 450 mL

B. 50 L

C. 85 µL

D. 12 kL

E. 3.5 × 102 dL

2. Which measurement represents the largest quantity?

A. 4730 ng

B. 4.73 × 10-4 g

C. 4.73 × 103 µg

D. 4.73 × 10-6 kg

E. 47.3 mg

3. Which of the following numbers contains five significant figures?

A. 0.04910

B. 0.4910

C. 4.9100

D. 49,100

E. 4,910,000

4. What is the total length of two pieces of tubing which measure 4.5 cm and 3.222 cm? Express the answer to the correct number of significant figures.

A. 3.722 cm

B. 4.722 cm

C. 7.722 cm

D. 7.7 cm

E. 8 cm

5. An analysis showed a sample to contain 0.00471 grams of lead. How many micrograms is this?

A. 0.471 µg

B. 4.71 × 103 µg

C. 4.71 × 106 µg

D. 4.71 × 10-2 µg

E. 4.71 × 10-6 µg

6. How many ng are there in 5.2 mg?

A. 1.9 × 102 ng

B. 1.9 × 105 ng

C. 5.2 × 103 ng

D. 5.2 × 106 ng

E. 5.2 × 109 ng

7. What is the area of a piece of metal foil that measures 43.9 cm by 29.21 cm? Express the answer to the correct number of significant figures.

A. 128 cm2

B. 1280 cm2

C. 1282.3 cm2

D. 1282.32 cm2

E. 1282.319 cm2

8. What is the numerical value of http://i127.photobucket.com/albums/p138/crazeegrrl0972/Math.jpg ? (Sorry, that’s a picture of it because my computer won’t show it)

A. 1.2

B. 1.2 × 1011

C. 1.2 × 107

D. 1.2 × 105

E. 1.2 × 103

9. How many calories are released when 500 g of water cools from 95.0°C to 25.0°C?

A. 35.0 cal

B. 70.0 cal

C. 1.25 × 104 cal

D. 3.50 × 104 cal

E. .4.75 × 104 cal

10. What is the volume of a gold nugget that weighs 2.20 kg? The density of gold is 19 g/cm^3

A. 8.60 × 103 cm3

B. 116 cm3

C. 11.6 cm3

D. 8.60 cm3

E. 0.116 cm3

Please be absolutely POSITIVE of the answers in your reply. Also, this is needed before 11:45pm PST, it is about 9:25pm PST currently.

Thank you greatly for any help.

Answer 1

1. 1 gallon =3.79 L

So, the closest answer is 50 L(B)

2. 4730 ng=4730*10^-9 g= 4.73*10^-6 g

4.73 × 10-4 g

4.73 × 103 µg=4.73*10^3*10^-6 g=4.73*10^-3 g

4.73 × 10-6 kg=4.73*10-6*10^3 g = 4.73*10^-3 g

E. 47.3 mg =47.3*10^-3 g=4.73*10^-2 g

So the largest quantity is E

3. C because 0 after the decimal point is only considered if it is after the value

4.D because if we add 2 numbers we take the least significant number

5.0.00471 grams=4.71*10^-3 g = 4.71*10^-3*10^6 µg = 4.71*10^3 µg (B)

6. 5.2 mg=5.2 * 10^-3 g=5.2*10^-3 *10^9 g = 5.2 * 10^6 (D)

7.B, like no 4, when we multiply 2 numbers, we also take the least significant number, A can't be chosen because it gives us diffferent result

8.(3*10^6)(2*10^-3)/(5*10^-2)=(3*2/5) *(10^6*10^-3/10^-2)=6/5 *10^(6-3-(-2))=1.2*10^5(D)

9.We know that Q=m*C* delta T, C water = 4200 J/kg K, m=0.5 kg, delta T=(25-95)=-70 C=-70 K

so Q=0.5*4200*-70=-147000 Joule

1 joule = 0.24 Calories So -147000 joule=-35280 calories( it releases 35280 calories --> D)

10. m=2.2 kg=2200 g

density=m/V

19=2200/V

V=2200/19=115.789 cm^3 (C)

Answer 2

yeah ok seriously its friday

do your own homework

Answer 3

3) A