What is the half life of a radioisotope if 25.0 grams of anoriginal 200.-gram sample of the isotope remainsunchanged after 11.46 days?3) 11.46 d1) 2.87 d4) 34.38 d2) 3.82 d
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Answer 1
Answer:
Half-life is the amount of time, in days or years( most common) a certain substance disintegrate half of it's content. We are given the initial (Ao) and final (A) amount of the substance. The time passed (T) is also given and we are asked to find the half-life (t). We use the equation below:
A=Aoe^(-ln2/t)T 25=200e^(-ln2/t)(11.46) Solve for t Answer: 3.82 days
How many miles of a gas sample are in a 20.0 l container at 373kand 203 kpa? the gas constant is 8.31 l-kpa/m-k
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To simplify our solution for this probelm we first assume that the gas we are dealing with is an ideal gas. Given that it is ideal we can proceed the solution using the formula: PV=nRT where P is pressure (203KPa), V is volume (20.0 L), n is moles (required), T is absolute temperature (373K) and R is the gas constant ( 8.31 l-kpa/m-k). Plug in the given to the respective variables and you should get 3.28 moles of the gas sample.
Which ion is part of every amino acid?
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In an amino acid, there are two ions present - the positively charged and the negatively charged. The positively charged is called the amino group while the negatively charged is the carboxyl group.
Particles are arranged in a crystal structure in a sample of:a) H2 (g) b) Br2 (L) c) Ar (g) d) Ag (s)
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The answer is number 4. Ag(s) or Solid Silver. Silver in a solid phase has a face centered cubic crystal structure. Among your choices, silver is the only example of particles that are arranged in their crystal structure while the other choices are gases and liquid. Liquid and gases have loose atoms that do not form crystal structures.
28 Which compound is an electrolyte? (1) CCl4 (3) C6H12O 6 (2) CH3OH (4) Ca(OH)2
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The answer is (4)Ca(OH)2. Electrolytes are substances that will ionize when dissolve in suitable ionizing solvents such as water. This includes such as salts, acids and bases. In the four choices, CCl4, C6H12O6 and CH3OH are nonpolar molecule.
What is the concentration of a 450 mL solution that contains 200 g of FeCl2?
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Molar mass FeCl₂ = 126.751 g/mol
450 mL / 1000 = 0.45 L
1 mole ------- 126.751 g ? mole ------- 200 g
moles = 200 * 1 / 126.751
moles = 200 / 126.751
= 1.57789 moles FeCl₂
M = n / V
M = 1.57789 / 0.45
= 3.50 Mol/L or M
hope this helps!
Which chemical equation below is balanced correctly? 3LiOH + Fe(NO3)3 yields LiNO3 + Fe(OH)3 2NaCl + CaO yields Na2O + CaCl2 Zn + HCl yields ZnCl2 + H2 Mg + HCl yields MgCl2 + H2
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The answer is 2NaCl + CaO yields Na2O + CaCl2. The balanced equation has the same number of the same element of the reactants and products.