The correct option is A.
To calculate the binding energy, you have to find the mass defect first.
Mass defect = [mass of proton and neutron] - Mass of the nucleus
The molar mass of thorium that we are given in the question is 234, the atomic number of thorium is 90, that means the number of neutrons in thorium is
234 - 90 = 144.
The of proton in thourium is 90, same as the atomic number.
Mass defect = {[90 * 1.00728] +[144* 1.00867]} - 234
Note that each proton has a mass of 1.00728 amu and each neutron has the mass of 1.00867 amu.
Mass defect = [90.6552 + 145.24848] - 234 = 1.90368 amu.
Note that the unit of the mass is in amu, it has to be converted to kg
To calculate the mass in kg
Mass [kg] = 1.90368 * [1kg/6.02214 * 10^-26 = 3.161135 * 10^-27
To calculate the binding energy
E = MC^2
C = Speed of light constant = 2.9979245 *10^8 m/s2
E = [3.161135 * 10^-27] * [2.9979245 *10^8]^2
E = 2.84108682069 * 10^-10.
Note that we arrive at this answer because of the number of significant figures that we used.
So, from the option given, Option A is the nearest to the calculated value and is our answer for this problem.
Answer:
10 m
Explanation:
The mole fraction of FeCl₃ of 0.15, that is, per mole of solution, there are 0.15 moles of FeCl₃ and 1 - 0.15 = 0.85 moles of water.
The molar mass of water is 18.02 g/mol. The mass corresponding to 0.85 moles is:
0.85 mol × 18.02 g/mol = 15 g = 0.015 kg
The molality of FeCl₃ is:
m = moles of solute / kilogram of solvent
m = 0.15 mol / 0.015 kg
m = 10 m
Answer:
B is correct → since temperature can be measured confidently and the variations with temperature are greater ( then the errors in measuring time diminishes)
Explanation:
A is not correct → since the sugar cubes will be still surrounded by water at the temperature chosen regardless of the size of the glass, organising the data by size of the glass is not correct since the glass size does not affect in a significant way to the results ( it could affect the cooling rate of water due to the exposed surface , it but would be insignificant)
C is not correct → since the sugar cubes are approximately of the same size , putting 2 cubes or "n" cubes will not affect the time significantly since each cube is still surrounded by water at the same temperature and behaves independently from others , then each cube dissolves at the same time ( there would be small variations due to the different sizes of the cubes and the small variation due to the limited mass of water)
D is not correct → since the solubility of sugar in water is high , the amount left after the experiment would be very small ( thus the relative errors are high) and the sugar would be contaminated with water in the weighting operation, leading to more errors
B is correct → since temperature can be measured confidently and the variations with temperature are greater ( then the errors in measuring time diminishes)
