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Sonia

@Miggi

Inactive

Posted: 15 years ago

#241

A poster is to have an area of 250 in ^2 with 3 inch margins at the bottom and sides and a 7 inch margin at the top. What dimensions will give the largest printed area?

I got length of 13 in and width of 19in. are they right?

Edited by Miggi - 15 years ago

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Sonia

@Miggi

Inactive

Posted: 15 years ago

#242

A piece of wire 28m long is cut into two pieces. One piece is bent into a square and the other is bent into an equilateral triangle.

How much wire should be used for the square in order to maximize

the total area?

I found it 28m
How much wire should be used for the square in order to minimize the total area?
and this one 12.18m

Are they correct?

Quote

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akhl

@akhl

Dazzler

Posted: 15 years ago

#243

Originally posted by: Miggi
A poster is to have an area of 250 in ^2 with 3 inch margins at the bottom and sides and a 7 inch margin at the top. What dimensions will give the largest printed area?

I got length of 13 in and width of 19in. are they right?

Do you need to round off your answers to nearest integers? I am getting

length = sqrt(150) = 12.25 = 12 in. (to nearest integer)

width = 250/12 = 21 in.

Quote

akhl

@akhl

Dazzler

Posted: 15 years ago

#244

Originally posted by: Miggi
A piece of wire 28m long is cut into two pieces. One piece is bent into a square and the other is bent into an equilateral triangle.

How much wire should be used for the square in order to maximize

the total area?

I found it 28m
How much wire should be used for the square in order to minimize the total area?
and this one 12.18m

Are they correct?

Correct. But see if website talks about any rounding off to any number of digits.

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Sonia

@Miggi

Inactive

Posted: 15 years ago

#245

i guess u r right for the first one but i'll make sure after submitting it. thnxxxx though :)

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Sonia

@Miggi

Inactive

Posted: 15 years ago

#246

Okaiii I am really confused on this question

It says naturally occuring lithium contains two isotopes: 6Li or Li-6(atomic mass of 6.0125) and 7Li or Li-7(atomic mass of 7.016). what is the %abundance of 6Li and 7Li in a naturally occuring sample of lithium?

These are the options:

a)92.4%6Li,7.6%7Li

b) 25.2%6Li,74.8%7Li

c)74.8%6Li,25.2%7Li

d)7.6%6Li,92.4%7Li

e)Insufficient information

2) What is the percent yeild if 185g of SiO2 are made from 328g of Cr2O3 by the following eq?

3Si + 2Cr2O3 ---> 3SiO2 + 4Cr

I got 95% is that right?

3) What mass of silver chromate will precipitate if excess K2CrO4 is added to 250.0mL of 0.183M Agno3?

I got 7.59g is that right?

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akhl

@akhl

Dazzler

Posted: 15 years ago

#247

Originally posted by: akhl

correct

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akhl

@akhl

Dazzler

Posted: 15 years ago

#248

???

There is only a picture from aishu_fan.😕

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Sonia

@Miggi

Inactive

Posted: 15 years ago

#249

Assuming ideal gas behaviour, which of the following gas samples will have the greatest volume at STP?

A) 1 g of Ar

B) 1 g of H

C) 1 g of O

D) All gases will have the same volume.

E) More data is needed to answer the question.

..........................................................................................................................

Which of the following gas samples would be most likely to behave ideally under the stated

conditions?

A) N

2 at 1 atm and -70C

B) CO at 200 atm and 25C

C) SO

2 at 2 atm and 0 K

D) Ne at STP

E) O

2 at 400 atm and 25C -------------------------------------------------------------------------------------------

Which of the following solutions has the lowest concentration of sulfate ion?

Hint: Assume that all sulfates listed here are strong electrolytes.

A) 0.1 M Al

2(SO4)3

B) 0.2 M MgSO

C) 0.3 M K

2SO4

D) All have the same concentration of sulfate ion.

E) None of the above is correct.

Please explain how did u do them too? :)

Edited by Miggi - 15 years ago

Quote

akhl

@akhl

Dazzler

Posted: 15 years ago

#250

Originally posted by: Miggi

Assuming ideal gas behaviour, which of the following gas samples will have the greatest volume at STP?

A) 1 g of Ar

B) 1 g of H
2
C) 1 g of O
2
D) All gases will have the same volume.

E) More data is needed to answer the question.[/quote]

Ans: B

At a given temperature and pressure, volume is proportonal to number of moles.

Number of moles = mass/molar mass

All have same mass (1 g). H2 has smallest molar mass, so the H2 sample has greatest number of moles and hence greatest volume.

..........................................................................................................................

[quoteWhich of the following gas samples would be most likely to behave ideally under the stated

conditions?

A) N
2 at 1 atm and -70C
B) CO at 200 atm and 25C

C) SO
2 at 2 atm and 0 K
D) Ne at STP

E) O
2 at 400 atm and 25C[/quote]
Will get back to it.

-------------------------------------------------------------------------------------------

[/quote]Which of the following solutions has the lowest concentration of sulfate ion?

Hint: Assume that all sulfates listed here are strong electrolytes.

A) 0.1 M Al
2(SO4)3
B) 0.2 M MgSO
4
C) 0.3 M K
2SO4
D) All have the same concentration of sulfate ion.

E) None of the above is correct.
Please explain how did u do them too? :)