Answers created by Oliver S.

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• How to solve with integration?
  
• Why did Great Britain declare war on Germany?
  
• For λ = 5.0 X 10^5m calculate the (i) fractional uncertainty in d. (ii) percentage uncertainty in d^2 ?
  
• Urgent. Please help. Calculate the percentage uncertainty for the displacement when t = 40s?
  
• How do I found the value of b? The answer is 4.7×10^4 to 5.3×10^4
  
• Would wearing sunscreen and/or wearing a thick jacket protect you from gamma radiation??
  
• Why is platinum used in electrochemical cells?
  
• What would be the empirical formula of ethane?
  
• Calculating the radius of a star 100 times bigger than our Sun?
  
• Are they both right? why?
  
• After World War II, who controlled North Korea? South Korea?
  
• Given pKa of weak acid HX is 4.2, what is the buffer created by mixing equal volume of 0.2M HX with 0.1 M NaOH?
  
• Write the chemical reaction showing comlete combustion of the organic substance formed in sodium hydroxide and chloroethane?
  
• How long does a ball take to fall from a roof to the ground 7 m below?
  
• The half-life of Tungsten-181 is 121 days. If you start with 3 pounds of it, how much do you have after 7 years?
  
• Two charges `+1*10^-6` and `-4*10^-6` are separatd by a distance of 2 m. Where is the null point located?
  
• What is the electron configuration of `"Cr"^(2+)` ?
  
• Why did some nations embrace totalitarianism after World War I?
  
• Mention 4 elements which exhibit allotropy?
  
• What is the derivative of `(3+2x)^(1/2)`?
  
• An iron piece get heated faster than water even though same amount of heat energy is applied in both.why?
  
• How many significant figures are there in 0.00707?
  
• How do you differentiate `f(x)=2sinx-tanx`?
  
• Calculate the pH of the following aqueous solutions?
  
• What is the observation that will made when bromine added to potassium fluoride?
  
• Please help with this question on functions?
  
• 1) How do enzymes actually work to speed up chemical reactions?
  
• The half-life of an isotope of tritium is 4500 days. How many days will it take an amount of tritium to fall to a quarter of its initial mass?
  
• A train whistle blows every 10 seconds. What is the frequency of the whistle?
  
• What is the ratio of lactic acid (Ka = 1.37x10-4) to lactate in a solution with pH =4.59?
  
• Is `f(x)=-4x^3+4x^2+2x-1` increasing or decreasing at `x=2`?
  
• How do you solve using elimination of `4x-5y= -1` and `2x+y=5`?
  
• Whatis the percent hydrogen in NaHCO3?
  
• Uranium-238 decays very slowly with a half life of 4.5 billion years. what percentage of a sample of uranium-238 would remain after 13.5 billion years?
  
• If 30 mL of 0.10 M NaOH is added to 40 mL of 0.20 M HC2H3O2, what is the pH of the resulting solution at 25°C? Ka for HC2H3O2 is 1.8 x 10^–5 at 25°C.
  
• What happened to Germany after WWII?
  
• How do you solve 2x-5y=-19 and 3x+2y =0?
  
• What are the points of inflection, if any, of `f(x)=2x^4-e^(8x`?
  
• What is the equation of the tangent line of `f(x)=6x-x^2` at `x=-1`?
  
• What protects us from harmful radiation of the sun?
  
• How was the presumed age of the Universe determined?
  
• What is the H-R diagram?
  
• What is the gravitational force that the Sun exerts on Jupiter?
  
• What will happen at the end of the sun's life?
  
• Can anyone give me some information on how nuclear energy is more beneficial than other types (GCSE level please :) ?
  
• What is the [H3O+] of a solution with the PH of 4.98?
  
• What are the units used to measure pressure?
  
• Consider a solution containing 4.62 g of a Group I metal carbonate, M2CO3 in a total volume of 100.0 mL. If 25.0 mL of this solution requires 20.0 mL of 0.5 mol L1 HCl for complete reaction, the Relative Atomic Mass of the metal M is?
  
• How do you graph `y=3cosx`?
  
• How do you balance `CuCl_2 + Fe -> 2Cu + FeCl_2`?
  
• How do you solve `3x^2+14x+15=0`?
  
• What is the slope and y-intercept of the line y=-5x+2?
  
• What is the pH of a solution that has a [H+] = 0.0039 M?
  
• What is the pH of a 0.003 M KOH solution?
  
• What are some common acids found in the home with the amount of pH valve it contains?
  
• What were the provisions of the Treaty of Versailles?
  
• Why did North Korea become communist?
  
• When wood is burned, new substances are produced. What kind of reaction is this and what type of change occurs?
  
• What's the equilibrium pH of an initially 0.64M solution of the monoprotic acid benzoic acid (HA) at `25^@ "C"` (Ka = 6.3 x 10^-5) ?
  
• What is the pH of the solution which results from mixing 20.0mL of 0.50M HF(aq) and 50.0mL of 0.20M NaOH(aq) at 25 centigrades? (Ka of HF = 7.2 x 10^-4)
  
• What's the OH- concentration in 0.48M CH3CO2- (aq) (Kb of CH3CO2- is 5.6 x 10^-10)?
  
• The pH of aquous 0.10M pyridine (C6H5N) ion is 9.09. What is the Kb for this base?
  
• How many moles are in 37.9 g of NaHCO3?
  
• Are dipole dipole forces weak?
  
• How do London dispersion forces relate to the boiling point of a compound?
  
• What is an aldehyde?
  
• What happens to hydrogen ions in a base ? and what is the equation ?
  
• N2o3 hybridization?
  
• How do you write 1000 in scientific notation?
  
• What are the properties of acids and bases?
  
• Titration Question - How many mL of 0.0350M NaOH are required to titrate 40.0 mL of 0.0350 M HNO3 solution to its equivalence point?
  
• Write half reactions for the following equation? : `Mg_((aq))^(+2) + Mn_((s)) -> Mg_((s)) + Mn_((aq))^(+4)`
  
• Why is absolute zero important?
  
• What is the limit of `e^-x` as `x to oo` ?
  
• Why is respiration considered as an exothermic reaction?
  
• What is the difference between an atom and an element?
  
• You serve a volleyball with a mass of 2.1 kg. The ball leaves your hand with a speed of 30 m/s. How much energy does the ball have?
  
• A ball with a mass of `350 g` is projected vertically by a spring loaded contraption. The spring in the contraption has a spring constant of `16 (kg)/s^2` and was compressed by `7/4 m` when the ball was released. How high will the ball go?
  
• How do you factor `y=n^2-16n+64`?
  
• What is the electron configuration for nickel?
  
• What is the cofficient of Cr^2+?
  
• How does Newton's third law apply to baseball?
  
• Sodium-24 has ahalf-life of about 15 hours how much of an 1.60 gram sample of sodium-24 will remain after 60.0 hours? Ans :(1g)?
  
• How do you convert 250% into decimals and fractions?
  
• What is `3^(3/2)` in radical form?
  
• What electromagnetic waves are used for communication?
  
• Seawater has a pH of 8.100. What is the concentration of OH–?
  
• What is the pH of a solution that is 5.0×10−2 M in H2CO3?
  
• If it takes 54 mL of 0.100 M NaOH to neutralize 125 mL of an HCl solution, what is the concentration of the HCl?
  
• The acid dissociation constant of `"H"_2"S"` and `"HS"^-` are `10^-7` and `10^-13` respectively. The pH of 0.1 M aqueous solution of `"H"_2"S"` will be?
  
• The correct order of increasing acidic nature is?
  
• Which of the given salt will have maximum pH?
  
• John uses a pulley to lift the sail on his sailboat. The sail weighs 150 N, and he must lift it 4.0 m. The pulley is 50% efficient. How much work must be done to lift the sail? How much work must John do on the rope to lift the sail?
  
• Would you agree with this? "Objects with mass has a property called inertia, Inertia means that objects has a tendency to resist all changes in motion that effects the object ",
  
• How to do this question?
  
• A bicycle possesses 1000 units of momentum. What would be the bicycle's momentum if its velocity is doubled?
  
• How do windmills make electricity?
  
• Why is a knife a wedge?
  
• How do you define sound intensity?
  
• On the EM Spectrum, which type of wave has the most energy?
  
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