In radioactive decay process, the negatively charged emitted β-particles are.
the electrons present inside the nucleus
the electrons produced as a result of the decay of neutrons inside the nucleus
the electrons produced as a result of collisions between atoms
the electrons orbiting around the nucleus
Which of the following statements is true for nuclear forces?
They obey the inverse square law of distance.
They obey the inverse third power law of distance
They are short range forces
They are equal in strength to electromagnetic forces.
A nucleus nXm emits one α and two β - particles. The resulting nucleus is.
nXm-4
n-2Ym-4
n-4Zm-4
None of these
Half-life of a radioactive substance is 12.5 h and its mass is 256g. After what time, the amount of remaining substance is 1 g?
75h
100h
125 h
150 h
The constituents of atomic nuclei are believed to be.
Neutrons and protons
Protons only
Electrons and protons
Electrons, protons and neutrons
Alpha particles are
2 free protons
helium atoms
singly ionised helium atoms
doubly ionised helium atoms
What is the radius of iodine atom? ( Atomic No. 53, Mass No. 126).
2.5 × 10-11m
2.5 × 10-9m
7 × 10-9 m
7 × 10-6 m
A sample of radioactive element has a mass of 10 g at an instant t = 0. Calculate the approximate mass of this element in the sample after two mean lives ?
3. 70 g
6 . 30 g
1 . 35 g
2. 50 gs
A free neutron decays into a proton, an electron and.
A beta particle
An alpha particle
an antineutrino
a neutrino
The most penetrating radiation out of the following is.
-rays
α- particles
β - rays
X-rays
