It’s c I believe because it says 209 years to complete an orbit so hint yourself ?.....
Answer:
Length = 393pm, Density = 21.3 g/cm^3.
Explanation:
From the question above, we have the following parameters or data which is going to aid in solving the above Question.
=> The radius of a platinum atom = 139 pm.
Therefore, the length can be calculated by making use of the formula given below:
Length = 2 √( 2r) = 2 × √ (2 × 139 × 10^-12m ) = 393 × 10^-10 m = 393pm.
The density can be calculated by making use of the chemical formula given below:
Density = mass ÷ volume = (195.064/ 6.02 × 10^23) ÷ (3.93 × 10^-10/ 10^-2) = 21.3 g/cm^3.
The mass of sulfur in the sample is 0.31g
To calculate mass of sulfur in sample: given that amount galena is 2.34g and mass of lead is 2.03 g as galena contain both lead and sulfur the mass of sulfur = mass of galena- mass of lead , that is, 2.34- 2.03=0.31g.The molecular mass is a algebraic sum of atomic mass of each element in the compound thus the mass of the compound can be obtained by adding atomic of each element. Lead(II) sulphide occurs naturally as the mineral galena, often known as lead glance (PbS). It is a significant source of silver and the most significant lead ore.
To learn more about mass:
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Answer:
CaCO₃ built up in hot water pipes
Explanation:
The hardness of water is classified as;
Permanent Hard Water:
In this the mineral content cannot be removed by boiling. This water contains mainly following,
Calcium Sulfate CaSO₄
Calcium Chloride CaCl₂
Magnesium Sulfate MgSO₄
Magnesium Chloride MgCl₂
These salts does not precipitate out on heating water.
Temporary Hard Water:
In this water the mineral content can be removed by boiling. This water contains mainly following,
Calcium Bicarbonate Ca(HCO₃)₂
Calcium Carbonate CaCO₃
Magnesium Bicarbonate Mg(HCO₃)₂
Magnesium Carbonate MgCO₃
These salts does not precipitate out on heating water. i.e.
Ca(HCO₃)₂ -------heat------> CaCO₃ + CO₂ + H₂O
The CaCO₃ are formed in the form of scales.
Result:
Hence, we can say that that CaCO₃ built up in hot water pipes.