Answers created by Andrea B.

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• A 75 kg bobsled is pushed along a horizontal surface by two athletes. After the bobsled pushed a distance of 4.5 m starting from rest, its speed is 6.0 m/s. What is the magnitude of the net force on the bobsled?
  
• What is a property that only some metals have?
  
• All measurements contain some error. Why is this a true statement?
  
• The intensity of sunlight at the Earth's surface is about 1000W/m^2. The average temperature of the Earth is about 58°F. What must the emissivity of the Earth be?
  
• What is the pH of a 4.8 x 10^-10 M H+ Solution?
  
• How do you find slope and intercepts to graph #y=2x-3#?
  
• A thermopane window consists of 2 glass panes,each 0.5cm thick,with 1cm thick sealed layer of air in between. Inside 23°C outside 0°C. Determine the rate of energy transfer through 1m² of the window?
  
• A #5 L# container holds #12 # mol and #9 # mol of gasses A and B, respectively. Every three of molecules of gas B bind to four molecule of gas A and the reaction changes the temperature from #360^oK# to #420 ^oK#. By how much does the pressure change?
  
• How does multiplying several measurements affect precision?
  
• The head of a rattlesnake can accelerate at 50 m/s^2 in striking a victim. If a car could do as well, how long would it take to reach a speed of 100 km/h from rest?
  
• Earth absorbs 10^22 energy from sun everyday. What will be percentage increase in the mass if mass of earth is 6*10^24 Kg?
  
• How does the activation energy affect reaction rate?
  
• An escalator carries 20 passengers of average mass of 60 kg. It travels 4.2 m in height in 1 minute each floor. What is the minimum power for the escalator to lift these passengers from the first floor to the third floor? (Take g = m / s^2)
  
• How does heat affect a chemical reaction?
  
• A car traveling at 50 mph goes around a curve that has a radius of 75 feet. What is the car's angular velocity in revolutions per minute to the nearest tenth?
  
• The area of a trapezoid is 60 square feet, its height is 6 ft, and one base is 12 ft. What is the number of feet in the other base?
  
• Compute ∑x for the following scores:5,4,6,5, and 4? a) 24 b) 20 c)23 d)21
  
• If I want heat 60degrees the 30liters of within 5mins, how much wattage is required..??
  
• Can you please explain the steps when you answer ? A laboratory ultracentrifuge is designed to produce a centripetal acceleration of 0.35x10^6 g at a distance of 2.50 cm from the axis. What angular velocity in rev/min is required?
  
• Are hydrogen fuel cells a viable alternative to gasoline?
  
• If a #3kg# object moving at #1 m/s# slows down to a halt after moving 2 m, what is the friction coefficient of the surface that the object was moving over?
  
• What is the formula of methyl ketones?
  
• How many moles are there in #5.3 times 10^23# atoms of gold?
  
• An object with a mass of #5 kg# is on a surface with a kinetic friction coefficient of # 3 #. How much force is necessary to accelerate the object horizontally at #6 m/s^2#?
  
• How do you determine the density of water vapor at different temperatures?
  
• A piston whose area is 50 cm 2 moves through a distance of 30 cm against a pressure of two atmospheres. Calculate the work done in Lt. atm., Nm and calories?
  
• Which two elements have similar characteristics?
  
• What are the different types of acids?
  
• What are Reducing Agents? And why are they used in chemical reactions?
  
• Ammonium nitrate dissolves in water to form ammonium ions and nitrate ions. You decide to determine the enthalpy of this dissociate since it is a type of reaction. ?
  
• How does molar mass affect the freezing point?
  
• A 131 kg car is at rest at the top of a 39 m high hill. If the car rolls down a frictionless hill, how fast will it be moving when it reaches ground level?
  
• Why is using a graduated cylinder more accurate than using a beaker?
  
• If two quantities have same dimensions ,do they represent same physical content?
  
• A 70 kg person climbs up 2 meters in 2.8 seconds. How much energy did they gain? How much power did they use?
  
• If an object is moving at #1 m/s# over a surface with a kinetic friction coefficient of #u_k=5 /g#, how far will the object continue to move?
  
• What type of exhaust comes from a Steam Engine, Internal Combustion Engine, and a Hydrogen Fuel Cell?
  
• What is the ideal gas law used for?
  
• What is the dimensional formula of Bernoulli's theorem?
  
• How can I calculate the buoyant force of a boat?
  
• Describe all 4 quantum numbers for last electron of 3d^5?
  
• At what point (in km from Earth) between Earth and Saturn is the net force of gravity on a body by both Earth and Saturn exactly zero?
  
• How much heat is required to melt 185 grams of ice at 0-degree Celsius and then raise the temperature of the resulting water to 32.0 degrees Celsius?
  
• What are strong and weak bases?
  
• 400g of water at temperature 15°c is placed in an electric kettle.The power rating of kettle is at 3.0kw.calculate the energy required to raise the temperature to 100°c?
  
• A circle has a center that falls on the line #y = 2/3x +7 # and passes through #(5 ,7 )# and #(1 ,2 )#. What is the equation of the circle?
  
• How does density affect fluid flow?
  
• Liquids generally have lower density as compared to solids but you must have obtained that ice floats on water, why ?
  
• Why is mercury ideal for use in thermometers?
  
• What is bad about nuclear power?
  
• What is the answer ?
  
• How much work does it take to raise a #9 kg # weight #15 m #?
  
• What does resistance of a fluid flow depend on?
  
• What is the kinetic energy of an object with a mass of #3 kg# that has been in freefall for #2 s#?
  
• Compare the solubilities of the following compounds in water: NH3, N2, NHC7H13, NH4Cl ?
  
• How to solve this basic kinematics problem?
  
• What is the difference between Altitude pressure and Atmospheric pressure?
  
• Air contains 24% oxygen and 78% nitrogen by mass (weight) . calculate the quantity of air ( mass of air ) required for complete combustion of unit mass fuel?
  
• Arrange in decreasing order of strength: Covalent-ionic-metallic bonds. Intuitive reasons are welcome?
  
• An object with a mass of #3 kg# is hanging from a spring with a constant of #8 (kg)/s^2#. If the spring is stretched by #4 m#, what is the net force on the object?
  
• How matter is conserved during chemical reactions?
  
• Deciding current in a circuit?
  
• A helicopter ascending upawards throws a stone downwards. Is the displacement or velocity of the stone negative?
  
• Silver chromate is sparingly soluble in aqueous solutions. The Ksp of Ag2CrO4 is 1.12× 10^–12. What is the solubility (in mol/L) of silver chromate in 1.50 M potassium chromate aq solution? In 1.50 M silver nitrate aq solution? In pure water?
  
• 2 kg and 4 kg are held with a compressed spring between them. If the masses are released,. If the smaller mass moves off with a velocity of 6m/s, what is the stored energy in the spring when it is compress ?
  
• A device operating at a potential difference of 1.5 volts draws a current of 0.20 ampere. How much energy is used by the device in 6.0 seconds?
  
• What is the normality of #0.3 M# of #H_3PO_4#?
  
• 6 Li + Ca3(BO3)2 ---> 3 Ca + 2 Li3BO3 How many grams of calcium metal would be produced if you started the reaction with 10 grams of calcium borate?
  
• How many atoms are there in one mol of carbon?
  
• A greenish blue solid A is heated. It gives off a colourless gas B and leaves a black solid C (i) Name the Compound A? (ii) Name the compound C?
  
• What an atom of 17Cl is joined with an atom of 11Na the product will be an ionic compound but when two atoms of Chlorine are joined together the product will be a Covalent molecule ?
  
• The kinetic energy of an object remains constant during an elastic collision. Is that true or false?
  
• The mass and diameter of a steel ball were used to determine its density the mass was measured within 1% dm3 the diameter within 3% what is the percentage error in the calculated density of the steel?
  
• A cell is connected in series with a resistor and supplies a current of 4.0 A for a time of 500 s. During this time, 1.5 kJ of energy is dissipated in the cell and 2.5 kJ of energy is dissipated in the resistor. What is the emf of the cell?
  
• How many grams of BaCl2 should be added to 300g H2O so that the freezing point of the solution is lowered to -8.3 degrees celsius? Assume that the BaCl2 completely dissociates in the solution. Thanks!
  
• 1 Joule of energy is to be converted into new system of units in which length is measured in 10 metre, mass in 10kg and time in 1 minute. The numerical value of 1joule in the new system is?
  
• PbCl_2 is 2.4x10^-4. Its solutibility in g/L is (Pb= 207.2, Cl=35.5)? PbCl_2 (s) +H_2O (l) ⇌ Pb^+2 (ac) + 2Cl^- (ac)
  
• Describe the factors that affect viscosity? (Select which of the following statements are true. Select all that apply.)
  
• Find the maximum amount of water that can flow through 3 cm i.d.pie per minutes without turbulence .Take the maximum Reynolds nomber for nonturbulent flow to be 2000?.for water at 20 c, viscosity=1*10^-3 pa.s Ans;0.0028 m^3
  
• A car initially at rest undergoes uniform acceleration for 6.32 seconds and covers a distance 120 meters. What is the approximate acceleration of the car?
  
• What volume of 0.80 M HCl would be needed to react with 4.0 g of CaCO3?
  
• What are the Differences between bending and stretching?
  
• A 25.0 ml sample of 0.150 M nitrous acid is titrated with a0.150 M NaOH solution. What is the pH at the equivalence point? theKa of Nitrous Acid is 4.50 x 10-4.
  
• What is the product of reacting benzene with #"1 mol"# of #"Cl"_2# catalyzed by #"FeCl"_3# in heat?
  
• What is the voltage produced in the following circuit? please show the calculations so i can understand it better and learn how to do it properly.
  
• What volume of carbon dioxide is produced when 25.0m2 of propane at atmospheric pressure is combusted?
  
• Solubility product of Al(OH)3 and Zn(OH)2 are 8.5*10^-23 and 1.8*10^-14 If NH4OH is added to a solution containing Al3+ and Zn2+ ions, then substance precipitated first is ?
  
• A cylinder of volume 1m3 is filled with 1kg of CO and 100g of H2O. What is the molar percentage of CO in the mixture in the cylinder?
  
• A mixture of He, Ne, and Ar has a pressure of 7.85 atm. If the Ne has a mole fraction of 0.47 and Ar has a mole fraction of 0.23, what is the pressure of He?
  
• On combustion, benzoic acid releases 26.38 KJ/g. The bomb calorimeter contained 1.000 g of benzoic acid. The temperature of the calorimeter rises from 24.32 degrees C to 27.05 degrees C?
  
• Arrange the following in order of increasing acidity Methane, carboxylic acid, phenol, alcohol?
  
• Why do liquids have a vapor pressure?Do all liquids have vapor pressures? Do solids exhibit vapor pressure? How does vapor pressure change with changing temperature?
  
• What is the overall voltage for a redox reaction with the half reactions #Ag^+ + e^(-) -> Ag(s)# and #Cu(s) -> Cu^(2+) + 2e^-#?
  
• In the reaction Na2CO3+HCl-> NaHCO3+NaCl,the equivalent weight of Na2CO3 is?
  
• Why Ph.Ph indicator is not used instead of methyl red indicator in the standardization of HCl solution by borax?
  
• A gas at a constant pressure of 95 kPa does 110 J of work as it expands from the volume #V# to the volume #2V#. What is the volume #V#?
  
• Rank the following 1.0M solutions from highest conductivity to lowest?
  
• What is the speed of an object that travels from #( -4,6,1) # to #( -1,4,-2 ) # over #2 s#?
  
• The solubility products of #Fe(OH)_2# and #Fe(OH)_3# are #10^(-17)# and #10^(-38)# respectively. If the concentrations of #Fe^(2+)# and #Fe^(3+)# are each #10^(-5)#, what is the #[OH^-]# when each just begin to precipitate?
  
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