Answer: Option B. -> Positively charged particles are concentrated at the centre of the atom
:
B
When alpha particles are sent through a thin metal foil only one out of ten thousand rebounded. Rutherford concluded that positively charged particles are concentrated at the centre of the atom.At the time of the experiment, the atom was thought to be analogous to plum pudding(as proposed by J.J. Thomson), with the negative charges (the plums) found throughout a positive sphere (the pudding). If the plum pudding modelwere correct, the positive "pudding", being more spread out than in the current model of a concentrated nucleus, would not be able to exert such large Coulombic forces, and the alpha particles should only be deflected by small angles as they pass through.

Answer: Option C. -> 2, 8, 1
:
C
Atomic number of sodium is 11. Thus, it contains 11 protons.
For a neutral atom, the number of protons is equal to the number of electrons. Hence, for sodium atom, the number of electrons =11.
The maximum no. of electrons that can be accommodated in a shell is given by $2\times n^2$, where n represents the no. of shell.
Hence, no. of electrons in
K shell = ($2\times 1^2$) = 2 electrons
L shell = ($2\times 2^2$)= 8 electrons
Now only one electron is remaining. Thus, M shell accomodates 1 electron.
Hence, electronic configuration of sodium atom is2, 8, 1.

Answer: Option A. -> True
:
A
According to Thomson's atomic model, the positive charge is uniformly distributed in the sphere and electrons are embedded in it just like a plum pudding.This implies that when alpha particles arebombarded on the atoms, they should get deflected uniformly.
However, in the Rutherford alpha particle scattering experiment, it was found thatrays were deflected in various angles.

Answer: Option A. -> J. J Thomson
:
A
J.J Thomson was the first scientist who measured charge to massratio(e/m) of anelectron. When a narrow beam of charged particles are projected at constant speed (v) across a magnetic field in a direction perpendicular to the field, the beam of particles experiences a force, which makes them move in a circular path.

Answer: Option D. -> −1.602×10−19 
:
D
An electron is a negatively charged subatomic particle.
It has a charge of $-1.602\times {10}^{-19}$ coulombs.

Answer: Option A. -> True
:
A
Atoms have electrons, protons, and neutrons as the fundamental particles.
$$\begin{array}{cc}\text{Subatomic particle}& \text{Mass (kg)}\\ \text{Proton}& \text{1.67262178}\times {10}^{-27}\\ \text{Neutron}& \text{1.6749}\times {10}^{-27}\\ \text{Electron}& \text{9.10938291}\times {10}^{-31}\end{array}$$
$\frac{Massofproton}{Massofelectron}$=$\frac{1.67262178\times {10}^{-27}}{9.10938291\times {10}^{-31}}$ = 1840
Thus, mass of electron is $\frac{1}{1840}$, i.e., 0.0005 times that of proton.
Hence, the mass of an electron is negligible when compared to the mass of proton.

Answer: Option D. -> All of these
:
D
Following are the properties of anode rays:
1) Anode rays deflect towards negatively charged plate.
2) Anode rays travel along a straight path in absence of electric and magnetic field.
3) Anode rays are positively charged radiations due to positive charged sub-atomic particles.

Answer: Option B. -> They are electrically neutral.
:
B
Gamma rays are electromagnetic radiations. They are electrically neutral in nature. They have no mass.

Answer: Option C. -> Neutral
:
C
An atom has always an equal number of electrons (negatively charged particles) and protons(positively charged particles), because of which there is no charge on the atom. Neutrons being neutral does not affect the charge of an atom.

Answer: Option B. -> K, L, M, N
:
B
The orbits or shells of an atom are represented as shown in the picture below. The nucleus is at the centre of the atom and the electrons in the shells around the nucleus. The shells in an atom are represented by the letters K,L,M,N and so on.