Only 2.50 mg of zirconium-86 remains from a 40.0-mg sample of zirconium-86 after 66 hours.?
830914
b) 16.5 hours\n\n66 hours/4 half lives = 16.5 hours\n\nYou start with 40 mg.  After 16.5 hours, you're left with 20 mg.  After another 16.5 hours, you have 10 mg.  After another 16.5 hours, you have 5 mg.  After yet another 16.5 hours, you have 2.5 mg.
939721
If it's metallic, it could be sodium or potassium.
784503
i m surprised none of these  answers are correct \nthe correct answer is Metalliod
947440
The man was poisoned with a radioisotope called polonium210.\n4 grains of this substance is enough to kill and is tasteless when ingested.\nThe reason that it took so long to detect is because it is an Alpha emitter. Alpha particles are not detected by a Geiger counter and the didn't suspect polonium210 because its so rare.  It can only be obtained from nuclear reactors by bombarding a substance with neutrons.  Polonium210 only attacks living tissue meaning it can be stored in a paper bag and be safe but once ingested you are doomed.  A horrible way to go.
272997
ok i will TRY to help you. im not completely sure but i think i know what to do. basically, when you add K2Cr2O7, it splits up into 2 parts, the Ks and the Cr2O7s. the Cr2O7s react with the potassium dichromate and make products. so if it was titrated correctly (assume it is), then \n8.76mL * 1L/1000mL * 0.04988mol/L    mols were added\n= 0.0004369488 mol of Cr2O7 added. and this amount made all the potassium dichromate get used up (apparently).\nwhich means that 0.0004369488/2 mols of potassium were in the blood. (divided by 2 because for each mol of potassium, 2 mols of Cr2O7 were used). so 0.0002184744 mols of potassium were in the blood. and if you use the molar mass to convert that to a mass. and then divide it by 10.0002g. you should get the mass percent of blood alcohol. so 0.0002184744mol x [(2x12.01) + (4x1.01) + (1x16) + (1x1.01)]\n= 0.0002184744mol x 45.07 g/mol\n= 0.009846641208 g  and divide it by 10g to get the mass percent which is 0.098466%.\nhope this helps. let me know if u need more help. laterz
588354
might be  mercury compound(only  Mercury can dissolved gold))
482317
Atomic wt of Al is 13,Cu is 29,Zn is 30 and Fe is 26.So less atomic wt,Al contains more number of atoms in 50gm
831776
A few are:\nMg, Zn, Al, Fe, and Cu.  They will dissolve at different rates according to the activity series of the metals.
1035627
Zinc 50 mgs. However if it is due to sinus problems this probably won't work
1062254
Lol\nI actually did a test like this for my nephews science project last year.  Unless the formulas have changed the differences are completly negligent.  Their lasting time is about the same.
755668
Ok.  Let's do the math.\n\n#1 2 days if the half-life is 8 hours\n\nThere are 48 hours in 2 days.  That's 6*8.\nSo, it halved 6 times.\nThat's 1/2 * 1/2 * 1/2 * 1/2 * 1/2 * 1/2 = (1 /2)^6= 1 / 64\nSo, if you had 64 grams of material, there would be 1 gram left after 8 days, for example.  64 gram * 1/64 = 1 gram\n\n#2 300 years when half-life is 5 years\n\n300 / 5 = 60, which means it was halved 60 times.\n1/2 * 1/2 * 1/2 * (fifty-seven more times) = (1/2)^60 =\n = 8.67362*10^(-19)\nFor example, a mole of an element is 6.0221415×10^23 atoms of that element.  If that element had a half-life of 5 years, then after 300 years, there would be about 522,000 atoms left.
109271
This is from Mr. Jeffy:\n\nIf you know that 60.4% of the naturally occuring isotopes have an atomic mass of 68.9257 amu, then you know that the other 39.6% much have an atomic mass such that the averge is 70.9249 amu.\nSo,\n(60.4% of 68.9257) + (39.6% of x) = 70.9249\nSo solve for x.\n============================================================\n\nI think he merely switched a couple of terms here, so I think the equation will look like this:\n\n(60.4% of 68.9257) + (39.6% of 70.9249) = x\n\nSolving:\n\n41.6311228 + 28.0862064 = (approx.) 69.72\n\nYou have gallium (Ga), my friend.
623715
The sample is 1/8 its original size, or 1/(2^3), after 7.5 minutes.  That means it has decayed three times in 7.5 minutes, or about once every 2.5 minutes.
223643
because not all of it has turned into lead yet. a half life extends forever. the part that has not decayed is still uranium.
212037
I think you are talking about Aluminum zirconium tetrachlorohydrex gly (used in anti perspirants). the molecular formula is\n\nAlyZr(OH)3y+4-xClxmGlynH2O
605534
TrueGentalman, Actually Such element DOES Exist.  Read on...\n\nErbuim has the atomic number of 68, but its Mass is not 68 amu.  It is actually 167.26 amu or 167.26g/mol.  Although it appears that no element has the exact mass of 68 amu in periodic table, Zinc having mass of 65.39 has a mass very close to 68.\n\nThe fact that Zinc has mass with a decimal suggests that it has isotopes and Zinc indeed has many isotopes.  \n\nThe TRUE answer to this question is Zinc-68.  It is a naturally occurring stable isotope of Zinc having atomic mass of exactly 68 amu.  \n\nI hope this helps.
836906
I had to read about this in order to answer your question at this web site:\n\nhttp://home.um.edu.mt/chemistry/CH230/2.Analytical/CP210a.PDF\n\nSo, two moles of DMG combines with each Ni++ ion.\n\n(0.2145 g Ni)* (1 mole Ni/58.71 g Ni) = 3.65*10^-3 mole Ni\n\nIf what you tell me is correct that DMG is 116.1194 then the Ni complex which loses 2 H+ for the Ni++ has a molecular wt of\n172.8134 (please double check)\n\n(3.65*10^-3 mole Ni)* (172.8134 g/mole) = 0.6314 g\n\nplease check for errors