Answer:
a)The total number of platinum atoms are 
.
b)The radius of a Pt atom is 138.7 pm.
Explanation:
a) Let the total number of platinum atoms be x
And mass of x atoms of platinum be m
Edge length of platinum cube ,s= 1.0 cm
Volume of the cube = 
Density of the platinum cube = 
Mass = Density × Volume
Mass of an atom of platinum = 
b) If only 74 percent of the space inside the cube is taken up by Pt atoms.
Volume occupied by platinum atoms = 74% of
Volume occupied by 
atoms is
.
The radius of a Pt atom is 138.7 pm.
This question is incomplete, the complete question is;
The area of the gold electrodes on the quartz crystal microbalance at the opening of Chapter 2 is 3.3 mm^2. One gold electrode is covered with DNA at a surface density of 1.2 pmol/cm2.
(a) How much mass of the nucleotide cytosine (C) is bound to the surface of the electrode when each bound DNA is elongated by one unit of C. The mass formula mass of the bound nucleotide is cytosine + deoxyribose + phosphate = C9H10N3O6P = 287.2 g/mol
Answer: mass of the nucleotide (c) bound is 11.37 g
Explanation:
Given that the area of gold electrodes = 3.3 mm^2
surface density of one gold electrode = 1.2 pmol/cm^2
that is to that in every 1 cm^2 of area, 1.2 pmol DNA is present
therefore
mass of nucleotide present in 3.3 mm^2 is;
= (1.2/100 * 3.3) pmol
= 0.0396 pmol
we were given that formula mass of the bound nucleotide = 287.2 g/mol
so
mass of the nucleotide (c) bound = ( 287.2 * 0.0396 )g
mass of the nucleotide (c) bound = 11.37 g
Molar mass Cu(OH)2 => 97.561 g/mol
Therefore:
1 mole Cu(OH)2 ------------ 97.561 g
? moles Cu(OH)2 ----------- 68 g
= 68 x 1 / 97.561
= 68 / 97.561
= 0.696 moles of Cu(OH)2
An adaptation is a mutation, or genetic change, that helps an organism, such as a plant or animal, survive in its environment.
