1. Science**updated asnwers**

5.B 6.A 7.C 8.D 9.A 11.D 13.D 5. Which of the following types of pollution cannot be attributed to car and truck emissions? A. acid rain B. sedimentation C. ozone D. photochemical smog 6. Which of the following is a source of photochemical smog? A. fossil

2. chemistry

Given these standard reduction potentials at 25oC: Cr3+ + e- -> Cr2+ (E1^o = -0.407V) Cr2+ + 2e- -> Cr(s) (E2^o = -0.913V) Determine the standard reduction potential at 25oC for the half-reaction equation: Cr3+ + 3e- -> Cr(s) This seems like a really

3. Social studies***help***

1.C 2.B 3.B 1.How would Bolivian society today most likely be different, if not for its Spanish colonial past? A. It would not have social inequalities of any kind. B. It would have a smaller population of indigenous peoples. C. It would not be dominated

4. physics

Three identical uniform meter sticks are placed on the floor. The first stick lies along the y axis from y = 0.320 m to y = 1.32 m. The second stick lies along the x axis from x = 0.330 m to x = 1.33 m. The third stick is positioned so that one end is on

5. Chemistry

carbon dioxide dissolves in water to form carbonic acid. Estimate the thermodynamic equilibrium constanst (K) for this reaction (delta Gf values: H2CO3= - 616.1, H2O= - 237.1, CO2= - 394.4) . Carbonic acid then ionizes in water (Ka1= 4.5 x 10^-7). Ignoring

6. Math - PreCalc (12th Grade)

The function f(x) = 2x + 1 is defined over the interval [2, 5]. If the interval is divided into n equal parts, what is the value of the function at the right endpoint of the kth rectangle? A) 2+3k/n B) 4+3k/n C) 4+6k/n D) 5+6k/n E) 5+3k/n

7. Chemistry-Repost for DrBob222

500 ml of a buffer solution with ph=2.10 must be prepared using .4 M HNO2 and solid KNO2. The ka value of HNO2 is 4e-3. a.) What mass of KNO2 should be added to 3 L of the HNO2 to make the buffer? b.) What is the buffer's pH after 150 ml of .5 M HNO3 is

8. physics

A person has a choice while trying to move a crate across a horizontal pad of concrete: push it at a downward angle of 30 degrees, or pull it at an upward angle of 30 degrees. If the crate has a mass of 50.0 kg and the coefficient of friction between it

9. Chemistry

The Heisenberg Uncertainty Principle: A student is examining a bacterium under the microscope. The E. coli bacterial cell has a mass of mm = 0.100fg\rm fg (where a femtogram, fg\rm fg, is 10−15g\rm 10^{-15}\; g) and is swimming at a velocity of vv =

10. math

Which expression represents the sum or (2x-5y) and (x+y)?

11. Biology

oil spills and leaks in the pacific ocean have harmed marine organisms and the environment. which kind of environmental issue is illustrated by this example? a) Resource Use b) Pollution c) Population Growth d) Biodiversity

12. math

How many faces, edges, and vertices does the solid figure have? image

13. Physics

You pull a sled across a horizontal frictionless patch of snow. If your pulling force is in the same direction as the sled's displacement and increases the kinetic energy of the sled by 34%, by what percentage would the sled's kinetic energy increase if

14. english

Which one of the following is a correct example of the singular possessive case? A. king's rights B. audiences' reaction C. women's club D. who's job I think it's C.

15. Math: Thinking Mathematically

A flagpole has the height of 16 yards It will be supported by three cables, each of which is attached to the flagpole at a point 4 yards below the top of the pole and attached to the ground at point that is 9 yards from the base of the pole, Find the total

16. math

The life of automobile voltage regulators has an exponential distribution with a mean life of six years. You purchase an automobile that is six years old, with a working voltage regulator and plan to own it for three years. a)What is the probability that

17. Algebra

Please explain how to do this problem. The answer says the answer is 2.43 inches, but I don't get it. A school wants to take out an ad in the paper congratulating a basketball on a successful season. The area of the photo will be half the area of the

18. Chemistry

The Heisenberg Uncertainty Principle: A student is examining a bacterium under the microscope. The E. coli bacterial cell has a mass of mm = 0.100fg\rm fg (where a femtogram, fg\rm fg, is 10−15g\rm 10^{-15}\; g) and is swimming at a velocity of vv =

19. Algebra

Simplify the expression, if possible. State the excluded values, if any. 1. 5x - 5/ 10x^2 - 25x + 15 2. w^2 + 6w + 9/ 2w^2 - 18 Thanks so much.

20. Physics

Help please A 200.0 g copper block absorbs 2.34 × 10^3 J of heat to raise its temperature by 30.0 K. What is the specific heat of copper?

50. statistics

the average act score submitted to a certain university is 26. to be eligible for admission, a student must score in the top 6% of applicants. if the scores are normally distributed with a standard deviation of 2.4, what is the minimum score needed to be

51. physics

if an airplane is traveling at 550 km/h into a head wind with a velocity of 40km/h what is the airplanes velocity relative to the ground

69. literacy

im in grade 10 and if i do the osslt literacy practice tests. will someone on here mark my writing tasks? i can mark the multiple choice questions on my own but i just need someone to mark the writing stuff

70. Math

What does Please Excuse My Dear Aunt Sally mean?

71. English

I'm writing about hearing a certain song can take you back to a moment in your past. I know that the 1st paragraph is thesis and the 2nd is explain what song reflects on past and why. I don't know what i should in include in the 3rd paragraph

72. language of medicine medical billing and coding

How does the musculoskeletal system change from birth to adulthood and what are the steps that the system goes through from childhood to adulthood to reach 206 bones?

73. PRE-CALC

If the original coordinate axes are rotated 45° to obtain the x' and y' axes, what is the value of x in terms of x' and y'?

74. Geometry

CD has an endpoint at (2,-1)and a midpoint at (8,3). which measure is closest to the length of CD?

75. english

Which synonym of the word look would be most effective in the following sentence? Detective Flint leaned forward with narrowed eyes to _______ what appeared to be a vital clue. A. survey B. scrutinize C. view D. ogle I think it's B.

76. Physics

A ball is traveling down a straight track at 20 m/s. How fast will the ball's speed be after it climbs a hill in the track that is 15 m high?

77. writing

How many supporting details should you develop to back up your thesis?

78. english

17. In which sentence is the word but used as a preposition? A. John liked baseball but not football. B. We would like to visit the Grand Canyon, but our vacation time is up. C. Children should be seen but not heard. D. None but the brave shall enter in.

79. Plays

Suppose something like this is in the script of a dramatic scene: MARY.[Scared] I don't know what happened. Is it okay if I have a period after "scared?" I know it isn't required, but is it wrong or still okay?

80. algebra

Write the equation in quadratic form and solve it by factoring. x2(8x + 65) 63 = x

81. math

describe a situation in which you might use each calculation a)9/8 divided by 2/3 b)1 and 2/3 divided by 2 and 2/3

in to kill mockingbird which character influences others more?

An example of an objective test is: A. short answers. B. essay-type exam. C. fill in the blanks. D. discussion board.

How many moles of Ca(OH)2 are needed to produce 82.9g of Ca3(PO4)2?

85. Physics

A 300 kg piano slides 4.4 m down a 30° incline and is kept from accelerating by a man who is pushing back on it parallel to the incline. The effective coefficient of kinetic friction is 0.40. (a) Calculate the magnitude of the force exerted by the man.

86. Physics

What is the minimum work needed to push a 1075 kg car 230 m up along a 17.5° incline? (a) Ignore friction. (b) Assume the effective coefficient of friction retarding the car is 0.30?

87. Math

The number of tickets sold each day for an upcoming performance of Handels Messiah is given by N(x)=-0.4x^2+11.2x+13, where x is the number of days since the concert was first announced. When will daily ticket sales peak and how many tickets will be sold

88. Statistics

An instructor hy pothesizes that the mean of the final ex am grades in her statistics class is larger for the male students than that it is for the female students. The data from the final ex am for the last semester are presented here. Test her claim

89. Math - PreCalc (12th Grade)

Use the inverse matrix to solve this system of equations: 4x+3y=7.5 7x+9z=14 4y-z=8.3 4,3,0 7,0,9 0,4,-1

90. math

A fruit seller bought m pears and twice as many mangoes. He also bought 10 fewer peaches than pears. Each pear cost RM 0.40 cents, each mango cost RM 0.50 cents while each peach cost RM 0.80. If the fruit seller paid RM 102. Find the value of m.

91. math

Rewrite the following equation in the center-radius form of the equation of a circle. x2 - 2x + y2 + 2y - 2 = 0

92. Statisics

To test the results of a conventional versus a new approach to the teaching of reading, 12 pupils were selected and matched according IQ, age, and present reading ability (there are 6 pairs!). One from each of the pairs was assigned to the conventional

93. Math - PreCalc (12th Grade)

The function f(x) = x2 − 5 is defined over the interval [0, 5]. If the interval is divided into n equal parts, what is the area of the kth rectangle from the right? A) [(2+k(5/n))^2+5](5/n) B) [(k(3/n))^2−5](5/n) C) [(k(5/n))^2+5](5/n) D)

94. Health

a boy notices a special needs student sitting by himself during recess. How can he get the student involved in a meaningful way? a- coach one of the teams b- be the all time referee c- the game be modified to allow for 2 goalies d- the game be played by

95. Math - PreCalc (12th Grade)

How many 4-digit numbers are possible if the hundreds digit is 8 and if repetition of digits is allowed? A) 100 B) 1,000 C) 9,000 D) 900 E) 1,800

96. Math - PreCalc (12th Grade)

The function f(x) = 6x + 5 is defined over the interval [-1, 4]. If the interval is divided into n equal parts, what is the value of the right end point of the first rectangle?

97. Chemistry

What is the pH of a solution prepared by mixing 24.6 g sodium acetate and 50 mL of 2.5 M acetic acid in a 500 mL flask and filling to volume

99. Algebra

Find a quadratic equation that has the numbers below as solutions. 1. 1/2,-10 2. 2/3,-5/7 How do I even do these problems? Those solutions are so hard to find.

100. Biology

Exogenous treatment with the plant hormone, ABA or auxin, induces enhanced susceptibility against biotrophic pathogens. Design an experiment that can reveal whether these hormones use the same signalling pathway or independent pathways to induce

101. physics

explain why a flat sheet of paper and a sheet of paper crumpled into a ball which are dropped from a height of 2 meters will not accelerate at the same rate?

121. algebra

solve by factoring a^2-4ab-8b^2?

122. Math - PreCalc (12th Grade)

A fair coin is tossed 3 times in a row. If X is the number of heads counted, what is the mean of the probability distribution of X? A) 1.0 B) 1.5 C) 2.0 D) 2.5 E) 3.0

123. Precalculus II

Find exactly all solutions in [0,2pi) to 4sin(x)cos(x) = 1