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Which evidence recorded at seismic stations following an earthquake supports the inference that Earth’s interior changes from solid rock to molten iron and nickel at the mantle-core boundary?
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Explain how copper replace hydrogen in this reaction although copper comes after hydrogen in chemical activity series ( by chemical equations) Cu + 4HNO₃ ⇒ Cu(NO₃)₂ + 2NO₂ + 2H₂O It's an o
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Is used in many home smoke alarms. if 10% of the americium in a smoke detector decays in 180 years, what is the half-life of this isotope?
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25cm^3 of a solution of X2O5 of concentration 0.100 mol/dm^3 is reduced by sulphur dioxide to a lower oxidation state. To reoxidise X to its original oxidation number required 50cm^3 of 0.02 mol/dm^3
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Human blood has a molar concentration of solutes of 0.30 m. what is the osmotic pressure of blood at 25°c? (r = 0.08206 l • atm/k • mol)
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Which concept describes the formation of four equivalent, single, covalent bonds by carbon in its compounds that resembles methane, ch4?
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Which atom in the ground state has the same electron configuration as a calcium ion in the ground state
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This unit discusses in detail the role of catalysts to lower the activation energy of reactions. The term catalyst appears in nonscientific discussions to refer to something that provokes or speeds si
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Chemistry please help I'm confused I don't understand how fe2+ ionic radius is less than ca2+. How is Fe2+ a smaller ion when it clearly has more electrons than ca2+ as shown in periodic table.
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Which of the following statements is true about the decomposition of a simple binary compound? The product could be an ionic or a molecular compound. The products are predictable. The reactants are t
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A 1 kg block of copper is hammered into a thin sheet. The length of the cooper sheet is 30 cm. What is the mass of the copper sheet
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Differentiate between various qualities of reagents including ordinary,analar and industrial quality reagents.
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Calculate the final temperature of a gas if 25.0 l of the gas at 25 degrees c and 1.00 atm is compressed into a volume of 2.50 l at a pressure of 5.0 atm. you must show all work to receive credit.
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Determine the wavelength of the light absorbed when an electron in a hydrogen atom makes a transition from an orbital in which n=2 to an orbital in which n=7. express the wavelength in nanometers to t
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Look at the resistor illustrated in the figure above.based on your knowledge of the resistor color code, what are the resistance value and tolerance of this resistor?A. 1.5k B. 2.7k
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Which of the following statements best describe how enzymes differ from ordinary chemical catalysts? A) Enzymes are inorganic in nature. B) Enzymes catalyze select chemical reactions. C) Enzymes bind
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When methanol is dissolved in water a non conducting solution results. when acetic acid dissolves in water, the solution is weakly conducting and acidic in nature. describe what happens upon dissoluti
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What mass of calcium can be produced by this process if a current of 6700 a is applied for 39 h ? assume that the electrolytic cell is 73 % efficient.what is the minimum voltage needed to cause the el
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It is required to make 14 grams of certain chemical compound called z. this is made from compounds w, x, and y in the ratio of 2:1:3. the compound y is itself made from w and x. to make 6 grams of y r
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An alpha particle (which is a helium nucleus, q=+2e, m=6.64×10−27kg) is emitted in a radioactive decay with ke = 5.63 mev .
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A 30.62 gram sample of chromium is heated in the presence of excess oxygen. a metal oxide is formed with a mass of 44.75 g. determine the empirical formula of the metal oxide.
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how can one convert 4.95×1022 atoms of zinc into grams?Many students experience difficulties in converting the atoms into grams. It is possible to convert the number of atoms into grams. This tutoria
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Niobium is an element whose density is 8.55 g/cm3 and atomic weight is 93. It crystallizes in body-body-centered structure. With this information, calculate the atomic radius of niobium atom.The quest
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When the following equation is balanced, the coefficient in front of HCl is: Ba(s) + HCl(aq)→BaCl2(aq) + H2(g) Question 4 options: 6 1 3 2
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Quartzite and marble can look very similar. Why do you think artists carve sculptures out of marble more often then quartzite?
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A watershed, or drainage basin, is a region of land where rain or snow drains downhill into a body of water, such as a river, lake, sea, ocean or wetland. The water in drainage basins is most likely u
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PLEASE HELP 22 POINTS How does heat differ from temperature? Temperature is the measure of heat. Temperature and heat are the same thing. Temperature measures thermal energy, and heat is the flow of t
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NEED HELP PLEASE I AM GOING TO FAIL A chemical reaction has an increase in entropy and a decrease in enthalpy. What is known about the spontaneity of the reaction? spontaneous at high temperatures, no
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Two ideal gases have the same mass density and the same absolute pressure. one of the gases is helium (he), and its temperature is 181 k. the other gas is neon (ne). what is the temperature of the neo
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The boiling point of an aqueous solution is 102.30 °c. what is the freezing point? constants can be found here.
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If you know the half-life of a radioactive isotope that occurs in an igneous rock, what must you measure to determine the age of the rock?
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How long would it take to obtain a carbon concentration of 0.75 wt% at a position 0.5 mm below the surface if the heat treatment were conducted at 725 ∘c ?
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For these expressions, energies are expressed in electron volts (ev) per na+–cl– pair, and r is the distance in nanometers (nm). the net energy en is just the sum of the preceding two expressions.
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Consider the reaction 2x2y2+z2⇌2x2y2z which has a rate law of rate= k[x2y2][z2] select a possible mechanism for the reaction.
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A solution is prepared as described in part a using solid cacl2⋅2h2o and de-ionized water.mass of weighing bottle and solid before transfer: 36.683 g mass of weighing bottle and solid after transfer
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A 0.610 m aqueous solution of kbr has a total mass of 61.0 g. what masses of solute and solvent are present?
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Select the answer with the correct number of significant figures for each calculation. 31.580 + 4.26 = 35.8 35.84 35.840
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Charissa says that bread goes through a chemical change when it is toasted. Which of the following observations would least support her conclusion? A. a change in the smell of the bread B. a change in
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Investigations were carried out in a science lab to explore the topic of chemical and physical changes. Investigation A Step 1. Add 5 tsp. salt to 100 ml warm water and stir until most or all of the s
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Please help if you have time: determine the percentage by mass of Chromium in the ore. I got the moles cro4- then divided by 2 to get moles of fe(cro2)2 because it's 4:2 ratio. Mark scheme doesn't do
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How many distinguishable slip systems are represented by {111} < 1 1 0 > in nickel at room temperature? explain?
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A voltaic cell consists of a hg/hg22+ electrode (e°= 0.85 v) and a sn/sn2+ electrode (e°= –0.14 v). calculate [sn2+] if [hg22+] = 0.24 m and ecell = 1.04 v at 25°c.
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What is the copper atoms in 1naira coin which weighs 7.39g assuming the material from which the coin is made is 86% copper.
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Calculate the volume of propylene (nu), which can be extracted from a propanol of 20 g, if the yield of the product is 87%.
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Chemistry, please help with part c only, if you have time, thanks. It's on titrations involving redox reactions.
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When 0.854 grams of a protein were dissolved in 88.9 ml of solution at 17.9 degrees c, the osmotic pressure was found to be 35.6 torr. calculate the molar mass of the protein?
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What is the boiling point of an benzene solution that freezes at 0.05 degrees c? normal freezing point is 5.5 and the normal boiling point is 80.1 degrees c. kfp = 5.12 k/m and kbp = 2.53 k/m. enter y
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Suppose instead that 5.00g ca is added to 50 ml of 1.00m hcl. determine the limiting recatant in this case and the number of moles
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Many experiments use gas manifolds to transfer gases from one reaction vessel to another. knowing the volume of such manifolds can be crucial. bulb a was filled with 540. ml of n2 gas. when opened to
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How many grams of solid magnesium nitrate (148.3 g/mol) should be added to 500 ml of 0.118 m of sodium nitrate in order to produce an aqueous 0.25 m solution of nitrate ions?
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