The mass number of aluminium is 26 and the atomic number of aluminium is 13.
The number of neutrons is given by the difference between the mass number and number of protons.
number of neutrons = mass number - number of protons
Number of protons = 13
Mass number of Aluminium = 26
Therefore number of neutrons = 26-13 = 13.
The atomic number of thorium is 90 and the mass number of thorium is 230 as given in the question
atomic number = number of electrons = number of protons
Therefore the number of electrons in thorium 230 = 90
Number of protons in thorium 230 = 90
Number of neutrons = Mass number - number of protons = 230-90 = 140
16. A
17. B
18. B
19. B
20. A
21. B
22. A
23. D
24. C
25. D
26. A
27. B
Explanation:
It is known that for a body centered cubic unit cell there are 2 atoms per unit cell.
This means that volume occupied by 2 atoms is equal to volume of the unit cell.
So, according to the volume density
![5 \times 10^{26} atoms = 1 [tex]m^{3}](https://tex.z-dn.net/?f=5%20%5Ctimes%2010%5E%7B26%7D%20atoms%20%3D%201%20%5Btex%5Dm%5E%7B3%7D)
2 atoms = 
= 
Formula for volume of a cube is 
. Therefore,
Volume of the cube =
As lattice constant (a) = 
= 
Therefore, the value of lattice constant is .
And, for bcc unit cell the value of radius is as follows.
r = 
Hence, effective radius of the atom is calculated as follows.
r =
= 
= 
Hence, the value of effective radius of the atom is .
Answer:
Iodine have higher atomic size than tellurium because of the presence of more number of protons and lower atomic mass than tellurium because of the presence of lower number of neutrons.
Explanation:
Atomic number of an element is the number of the protons present in the element.
Atomic mass is the sum of a protons and the neutrons which are present in the nucleus of the atom.
Iodine has higher atomic number than tellurium because it has more number of protons than the tellurium.
On the other hand, iodine has lower atomic mass than tellurium because it has less number of neutrons in its core.
