The density of copper is 8.96g.mL^-1. A cube of copper weights 2.66 kg. The edge
ID: 479442 • Letter: T
Question
The density of copper is 8.96g.mL^-1. A cube of copper weights 2.66 kg. The edge length of the cube is: 0.297 mm 1.50 mm 2.97 mm 3.37 mm 6.67 mm 15.0 mm 33.7 mm 66.7 mm None of the above; the correct time is _____ hours. A certain element, which consists in nature of only a single isotopic, has a mass number of 197 and an atomic number of 79. This element forms a 3+ ion. This ion has 79 neutrons 76 protons and 79 electrons. A certain element which consists in nature of only two isotopes, has one isotope with an atomic mass of 62.9396 amu and an abundance of 69.17%. The atomic mass of this element is 63.546 amu. The atomic mass of the other isotope is: 62.9296 63.2378 63.7515 63.8210 63.8542 64.1624 64.7788 64.9065 65.3952 None of the above; the correct atomic mass is ____ amuExplanation / Answer
4)We know the weight of copper cube = 2.66 kg; and it's density = 8.96 g/mL
Form this we can caluclate the volume of cube V= s^3= 2660 g/8.96g/mL= 296.875 mL = 296875 cubic mm
So, the lenght s = cubic root (296875)= 66.71 mm, (answer = h)
5) the atomic mass number = 197
atomic number = 79
So, the no. of protons = electrons = 79.
The ionic form as 3+ ion. So, 3 electrons are removed to form +3 ion.
The ion contains 76 electrons. But, the number of protons remain the same = 79.
No. of neutrons = atomic mass number - atomic number = 197-79 = 118.
Ans: This ion has 118 neutrons, 79 protons, and 76 electrons.
6) The atomic mass of the element = 63.546 amu;
Lets call isotopes as A and B;
Isotope atomuc mass = 62.9396 amu
Abundance of A = 69.17 %; so the fraction of A = Xa = 0.6917;
We need find the atomic mass of isotope B;
Abundance of B = 100-69.17 = 30.83% ; So, the faction of B= Xb = 0.3083
Average Mass =Mass A × Xa + Mass B × Xb
63.546 = 62.9396 x 0.6917 + Mass B x 0.3083
Mass of B = 64.9065 amu.
The atomic mass of the other isotope is 64.9065 amu(answer: h ).
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