Correct answer: has a completely filled outermost shell
Atoms of the element with complete outermost shells are stable. So, in order to attain stability the atom either loses electrons or gains electrons to completely fill the outermost shell. The stable electronic configuration for the s and p-block elements is exhibited by the noble gases or the group 8 elements. All the unstable atoms try to attain the electronic configuration of the nearest noble gas with completely filled outermost shell.
There are 3 major types of radiation. The Alpha, Beta and Gamma radiation. It is the Alpha radiation that can be stopped by a piece of paper or fabric. Beta on the other hand can be stopped by plastic or a thin sheet of metal and Gamma by a piece of aluminum foil or lead.
Answer: There are 7 alpha-particle emissions and 4 beta-particle emissions involved in this series
Explanation:
Alpha Decay: In this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. The mass number is reduced by 4 units and atomic number is reduced by 2 units.
Beta Decay : It is a type of decay process, in which a proton gets converted to neutron and an electron. This is also known as -decay. In this the mass number remains same but the atomic number is increased by 1.
In radioactive decay the sum of atomic number or mass number of reactants must be equal to the sum of atomic number or mass number of products .

Thus for mass number : 235 = 207+4X
4X= 28
X = 7
Thus for atomic number : 92 = 82+2X-Y
2X- Y = 10
2(7) - Y= 10
14-10 = Y
Y= 4

Thus there are 7 alpha-particle emissions and 4 beta-particle emissions involved in this series
Answer:
Explanation:
a) for 1.000 g X: 0.1621 g Y
ratio of mass of element Y = 2.100g : 0.1621g
= 1 : 0.07
b) 1.000 g X: 0.7391 g Y
ratio of mass of element Y = 2.100g : 0.7391g
= 1: 0.35 , = 20:7
c) 1.000 g X: 0.2579 g Y
ratio of mass of element Y = 2.100g : 0.2579g
= 1 : 0.12
d) 1.000 g X: 0.2376 g Y
ratio of mass of element Y = 2.100g : 0.2376g
= 1: 0.11
e) 1.000 g X: 0.2733 g Y
ratio of mass of element Y = 2.100g : 0.2733g
= 1 : 0.13
From the values obtained , the closest that is in compliance with the law f multiple proportions is option B