# Posts by Bob

Total # Posts: 3,282

chemistry
Using this data, 2 NO(g) + Cl2(g) == 2 NOCl(g) Kc = 3.20 X 10-3 NO2(g) == NO(g) + ½ O2(g) Kc = 3.93 calculate a value for Kc for the reaction, NOCl (g) + ½ O2 (g) == NO2 (g) + ½ Cl2 (g) A. 20.2 B. 2.06 X 10-4 C. 4.49 D. 4.84 X 10-3 E. 0.223 eliminated down...

Math
A bag has 4 red, 6 white, and 9 blue marbles. How many ways can 5 marbles be selected if 2 are one color, and 3 are another color?

PHi103
The truth table for a valid deductive argument will show

math
(4.35E-2 - x)(7.56E-2 -x ) ============================ (0.324 + 2x)2 Rearrange to get an expression of the form ax2 + bx + c = 0 and use the quadratic formula (solve for x. This gives: x = 1.05E-2, 0.143 basically i understand they use the quadratic equation but how did they...

english 11
just took it. Joyce has the right answers.

english 11
a b c d

physics
a 25000000 gr rocket is propelled from rest by an engine that produces a 312500 kgm/s2 for 1.375s A) What is the sleds acceleration? B) What is the velocity after 1.375s?

Math :(

Math :(
A rectangular pyramid with the base of 12 feet by 8 feet need to be filled with balloons. if the pyramid 16 feet tall, how much space is available for the balloons?

math
the outlier is 7 and the outlier is a number away from all the other ones,which in this case is 7.

math
Jean has 4 times as many marbles as Peter. If Jean gave 18 marbles to Peter, they would then have the same number of marbles. How many marbles does each have?

Chemistry
How many moles of nitric acid will be produced when .51 mole of dinitrogen pentoxide reacts

yes,Pi is an irrational number.

math
Determine the slope of a line passing through the points (2, 9) and (0.66, 9).

physics
Jabdbal

How do the surface proteins on a virus help it to invade a host cell?

algebra
3x+y=20 x+3y=12

Math
Parallel lines have the same slope so the slope of 3x-4y+5 =0 is y=(-3x-5)/-4 slope =3/4 therefore the y=(n-2)x+12 must have a slope of 3/4 so n-2=3/4 n=2.75 If the lines are perpendicular they have negative reciprocal slopes therefore n-2= -4/3 n=2-4/3 or 2/3

algebra
There are three important numbers coming from the factors, 0, -1, and 3 test using numbers around those numbers. Using -2 because it is less than -1 (-2)(-2+1)(-2-3) =-10 which is < 12 Using -.5 because it is between -1 and 0 (-.5)(-.5+1)(-.5-3)=.875 which is <12 Using 1...

Physics help?
A 170 -pF capacitor is connected in series with an unknown capacitance, and as a series combination they are connected to a battery with an emf of 25.0 V. If the 170 -pF capacitor stores 135 pC of charge on its plates, what is the unknown capacitance?

maths
Do the same thing you did before using -1/2 for x. (2x+1=0 and solve for x) Then you will have two equations and two unknowns and you can solve for p

math
x= total marbles x-(1/4)x what he had after 1st round (x-(1/4)x)-1/3(x-(1/4)x) what he had left after 2nd (x-(1/4)x)-1/3(x-(1/4)x)-1/2((x-(1/4)x)-1/3(x-(1/4)x)) what he had left after 3rd round which equals 2 (the one he gave to Shavana and the one he kept) (x-(1/4)x)-1/3(x-(1...

Math
When raising to a power multiply the exponents. 8.8*10^25

math
I do

francisco (:

You body consist of 7/10 water. Is more than 1/2 your body water? Explain

-3+5*(2(-6))=37

Trig
A pilot is flying over a straight highway. He determines the angles of depression to two mileposts, 6.7 mi apart, to be 36° and 41°, as shown in the figure

Physics
Smd

8 1/2 inches long into 1/2 inches long will be how many short pecies

Math
Words

Mathematics
What percentage is 2/27?

Physics
A 73kg sprinter, starting from rest, reaches a speed of 7.0 m/s in 1.8s, with a negliable effect due to air resistance. The sprinter then runs with the remained of the race at a steady speed of 7.0 m/s under the influence of a 35-N force due to air resistance. What is the ...

Math
It equauls 2sinx

Math
How do I solve: sqrt(3)tanx= I need to use the identity tanx=sinx/cosx Thanks

chemistry
If the reaction Cl2 (g) + O3 (g) = Cl2O (g) + O2 (g) occurred in just two steps, what would be the overall order of the reaction be? a. 1 b. 2 c. 3 d. 4 e. not possible to determine from the information given help

chemistry
The equation A + 2 B = C + D describes an elementary reaction, which takes place in a single step. Thus, the rate law must be a. rate = k(A]2 b. rate = k(B]2 c. rate = k(A][B] d. rate = k(A][B]2 e. none of the above represents the rate law for this elementary reaction. help

chemistry
The decomposition of hydrogen peroxide in solution and in the presence of iodide ion was studied in laboratory, and the following mechanism proposed based on the experimental data. H2O2 + I - = H2O + IO - (slow) H2O2 + IO - = H2O + O2 + I - (fast) Which one of the following ...

chemistry
A particular reaction has an activation energy of 51.6 kJ/mol-rxn. How much faster is the reaction at 50 degrees C versus 25 degrees C? a. 2 times b. 5 times c. 3 times d. half as fast d. 20% as fast help No one has answered this question yet.

chemistry
For a one step reaction, the activation energy for the forward reaction is 40.0 kJ/mol and the enthalpy of reaction is -20.0 kJ /mol. Which statement below is true? a. The activation energy of the forward reaction would be affected to a greater extent than the activation ...

chemistry
If the reaction Cl2 (g) + O3 (g) = Cl2O (g) + O2 (g) occurred in just two steps, what would be the overall order of the reaction be? a. 1 b. 2 c. 3 d. 4 e. not possible to determine from the information given

chemistry
A catalyst alters the rate of a reaction by a. changing the products in the reaction. b. increasing the activation for the reaction. c. always providing a surface on which the molecules react. d. providing an alternate pathway for the reaction. e. increasing the concentrations...

chemistry
The equation A + 2 B = C + D describes an elementary reaction, which takes place in a single step. Thus, the rate law must be a. rate = k(A]2 b. rate = k(B]2 c. rate = k(A][B] d. rate = k(A][B]2 e. none of the above represents the rate law for this elementary reaction.

chemistry
The decomposition of hydrogen peroxide in solution and in the presence of iodide ion was studied in laboratory, and the following mechanism proposed based on the experimental data. H2O2 + I - = H2O + IO - (slow) H2O2 + IO - = H2O + O2 + I - (fast) Which one of the following ...

chemistry
The reaction: A + 3 B = D + F was studied and the following mechanism was finally determined A + B = C (fast) C + B = D + E (slow) E + B = F (very fast) The step with largest activation energy is a. the first step b. the second step c. the third step d. none of the steps has ...

chemistry
For a particular chemical reaction, the rate constant at 30.0 °C is 1.38 X 10-4 L mol-1 s-1, while the value at 49.0 °C is 1.21 X 10-3 L mol-1 s-1 . What is the activation energy for this reaction? a. 92.8 kJ b. 200 kJ c. 40.4 kJ d. 343 kJ e. 56.4 kJ ln 1.38x 10 -4 / 1...

chemistry
For a certain chemical reaction, the rate constant at 250.0 °C is 0.00383 s-1 and the activation energy is 22.40 kilojoules. Calculate the value of the rate constant at 335.0 °C. a. 0.00513 s-1 b. 0.00946 s-1 c. 0.00787 s-1 d. 0.0224 s-1 e. 0.000640 s-1 b or c

chemistry
For a one step reaction, the activation energy for the forward reaction is 40.0 kJ/mol and the enthalpy of reaction is -20.0 kJ /mol. Which statement below is true? a. The activation energy of the forward reaction would be affected to a greater extent than the activation ...

chemistry
A particular reaction has an activation energy of 51.6 kJ/mol-rxn. How much faster is the reaction at 50 degrees C versus 25 degrees C? a. 2 times b. 5 times c. 3 times d. half as fast d. 20% as fast help

Math/Calculus.
Suppose (x^2)*(e^(-2y))= ln(xy) Find dy/dx by implicit differentiation.

chemistry
how does the electrolyte paste in a battery work

math
I have a rectangle w/ 20 boxes in it what would 1/5 of the boxes be?

calculus
The voltage signal from a standard European wall socket can be described by the equation V(t)=325sin100 pi x , where t is time, in seconds and V is the voltage at time, t. determine the period frequency and amplitude

English
Tree

physics/chemistry
so it is a physics project

physics/chemistry
if i'm testing conductivity of different salts?

physics/chemistry
is conductivity a physical or chemical property

math
a data set of size 19 has correlation coefficient of r= 0.432. Test the significance of r at the 5% level and at the 1% level

geometry
In the figure below, the measure of arc AC is 88 degrees if angle ABC is equal to 88 degrees.

math
Write as a single log of a single argument: log3 24 + log3 17 - log3 51

Math
For a class play, student tickets cost \$2 and adult tickets cost \$5. A total os 30 tickets were sold. If the total sales must exceed \$90, what is the miniuim number of adult tickets that must be sold?

algebra
31

chemistry
How many molecules of hydrogen gas are produced by the reaction of tin with 20.0 L hydrogen mono fluoride at STP

algebra
In 16 years, Ben will be 3 times as old as he is right now. How old is he right now?

PHYICS HELP
While a person is walking, his arms swing through approximately a 45° angle in .530s. As a reasonable approximation, we can assume that the arm moves with constant speed during each swing. A typical arm is 70.0 cm long, measured from the shoulder joint. 1) What is the ...

Math
What's the answer to "230 is increased to 250?"

math
8/year

Math
100

Math
25 times 4 is the man with purple eyes

Physics
Henrietta is going off to her physics class, jogging down the sidewalk at a speed of 2.05 m/s. Her husband Bruce suddenly realizes that she left in such a hurry that she forgot her lunch of bagels, so he runs to the window of their apartment, which is a height 43.9 m above the...

chemistry
Consider the reaction below: Cgraphite(s) + F2(g) +1/2O2(g) → CF2O(g) Which of the following is a correct rate expression? 1. rate = −2∆[O2]/∆t 2. rate = −∆[CF2O]/∆t 3. rate =∆[F2]/∆t 4. rate = −∆[Cgraphite]/&#...

Chemistry
Carbon dioxide gas has a solubility of 0.0972 g/100 g H2O at 40 degrees celsius. Expressed in parts per million, this concentration is closest to... (1)0.972 ppm (2)9.72 ppm (3)97.2 ppm (4)972 ppm

geometry
A regular hexagon has side lengths 15 in. The perimeter of the hexagon is 90 in. A second hexagon has side lengths 18.75 in. Find the perimeter of the second hexagon. Round to the nearest tenth.

algebra
A box of animal crackers measures 12 inches by 8 inches by 2 inches. What is the volume of the box?

algebra
The sum of three consecutive integers is -96. What is the largest integer?

algebra
The sum of three consecutive integers is . What is the largest integer?

algebra
Ky has 3 times more books than Grant, and Grant has 6 fewer books than Jaime. If the total combined number of books is 176, how many books does Jaime have?

math - integers
68 kms

Mathg

math
Side of Square is 25 feet. One side of rectangle is 30 feet and other is 20 feet.

math
512

math
72

math
35*6 is 210 not 200.

physics
in 1989 michel menin of france walked on a tightrope suspended under a balloon nearly at an altitude of 3150 m above the ground . suppose a coin falls from menin's pocket during his walk . how high above the ground is the coin when its speed is 60 m/s ?

physics
the largest watermelon ever grown had a mass of 118 kg. suppose this watermelon were exhibited on a platform 5 m above the ground . after the exhibition, the watermelon is allowed to slide along to the ground along a smooth ramp, How high above the ground is the watermelon at ...

physics
A Physics book , mass unknown , is dropped from a table . its velocity just before hitting the ground is 9.39 m/s . what is the height of the table ?

physics
a 20 kg rock is on the edge of a 100 m cliff . the rock falls from the cliff , what is its kinetic energy just before it hits the ground ?

physics
gtfo fag^

materials science
A bar of pure nickel is coupled with a bar of pure iron (interfaced). The diffusion couple is then heated to a temperature of 1000°C. (a) How long will it take for the concentration of nickel to reach 0.1 wt%, 1.0 μm below the interface? (b) How long will it take for ...

chemistry
6.8 grams

geometry
ABCD is a trapezoid with DC parallel to AB, AB=4, AD=4, angle A=60, angle C=45. Find DC and BC

chemistry
In a nickel bath with a total volume of 1000 gallons, titration of a 50 milliliter sample with 0.1 N silver nitrate used up 10.5 milliliters to the end point. What is the concentration in ounces per gallon of the nickel chloride (NiCl2 ) in the bath?

chemistry
A 10 milliliter sample of HCl pickle is titrated with 0.2 N NaOH to a phenol-phthalein end point and it is found that 6.5 milliliters are used. What is the concentration of HCl in the Pickle in grams per liter? In weight Percent?

math
Bob and Jack play a shooting game. In this game, they have a net at a distance. The net is made up of 1 mm thick wires. The wires run vertically and horizontally to form a mesh that has 5 mm square openings between them. A bullet 2 mm in diameter must be shot in such a way ...

physics
122

calculus
actually an ODE question(but there's no diff. eq. subforum) (y^2)(dy/dx)+y^3/x =2/x^2 using substitution u(x)=y^3 so I've been doing a few of these and getting them all wrong and this problem... I don't know where to start. I tried (1/u)(du/dx)+u/x(du/dx)=2/x^2 but...

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