Mass of electron is
1 / 1800 times mass of proton
1 / 1840 times mass of proton
1 / 1859 times mass of proton
1 / 1750 times mass of proton
The atoms having different number of protons and different number of electrons but same number of neutrons are called
Isotopes
Isobars
Isotones
None of these
Who discovered radioactivity?
Albert Einstein
Ernest Rutherford
Antoine Henri Becquerel
James Chadwick
The diagram shows the paths of three different types of radiation, X, Y and Z.
X-Beta particles , Y - Alpha particles, Z = gamma particles
X-Gamma particles , Y - Alpha particles, Z = Beta particles
X-Beta particles , Y - Gamma particles, Z =Alpha particles
X-Alpha particles , Y - Beta particles, Z = gamma particles
A radioactive substance is oxidised. What changes would you expect to take place in the nature of radioactivity ?
increases
decreases
remains constant
cannot be predicted
A certain nucleus X has a mass number 15 and atomic number 7.Find the number of neutrons.
15
7
8
22
The minimum amount of energy required to emit electrons from a metal surface is called the:
cohesive energy
work function
ionisation energy
dissociation energy
Which of the following radiations is least penetrating?
α - particles
β - particles
x - rays
γ - radiations
The work function of tungsten coated with barium oxide is nearly.
5 eV
10 eV
1 eV
0.01 eV
One isotope of uranium has a mass number 235 and atomic number 92.What is the number of electrons in the neutral atom of this isotope?
235
92
143
327
