NUCLEI

How many electrons are contained in ²³⁸₉₂U nucleus?

• 92

• 146

• 238

• 0

Chadwick was awarded the Nobel prize in Physics in 1935 for his discovery of:

• electron

• proton

• neutron

• None of these

The density of a nucleus is of the order of:

• 10¹⁵ kg m^-3

• 10¹⁸ kg m^-3

• 10¹⁷ kg m^-3

• 10¹⁶ kg m^-3

Nuclear force is:

• strong, short range and charge independent force

• charge independent, attractive and long range force

• strong, charge dependent and short range attractive force

• long range, change dependent and attractive force

Fusion takes place at high temperature because:

• Atom are ionised at high temperature

• Molecules break up at high temperature

• Nuclei break up at high temperature

• Kinetic energy is high enough to overcome repulsion between nuclei

The helium atom does not contain:

• two protons

• two electrons

• two neutrons

• six nucleons

The mass number of a nucleus is A and its atomic number is Z. The number of neutrons in the nucleus is :

• A – Z

• A

• Z

• A + Z

Ratio of the radii of the nuclei with mass numbers 8 and 27 will be:

• 1:1

• 27:8

• 2:3

• 4:9

Light energy emitted by star is due to:

• breaking of nuclei

• joining of nuclei

• burning of nuclei

• reflection of solar light

Sun’s radiant energy is due to:

• nuclear fission

• nuclear fusion

• photoelectric effect

• spontaneous radioactive decay