In the Geiger-Marsden experiment, a particles are scattered by gold nuclei. The experimental results indicate that most a particles are
A sample of radioactive carbon-14 decays into a stable isotope of nitrogen. As the carbon-14 decays, the rate at which the amount of nitrogen is produced
Which one of the following provides direct evidence for the existence of discrete energy levels in an atom?
A sample of material initially contains atoms of only one radioactive isotope. Which one of the following quantities is reduced to one half of its initial value during a time equal to the half-life of the radioactive isotope?
In a fission chain reaction,
Isotopes provide evidence for the existence of
An isotope of radium has a half-life of 4 days. A freshly prepared sample of this isotope contains N atoms. The time taken for 7/8 N of the atoms of this isotope to decay is
The presence of neutrons inside the nucleus is supported by the existence of
Ag-102, Ag-103 and Ag-104 are three isotopes of the element silver.
Radioactive decay is a random process. This means that
The number of nucleons in a nucleus is the number of
The emission and absorption spectra of different elements provides evidence for the existence of
The nucleus of an atom contains protons. The protons are prevented from flying apart by
The unified mass unit is defined as the rest mass of
Which one of the following provides evidence for a nuclear model of the atom?
Which of the following identifies the significant interaction(s) between nucleons inside the nucleus?
A sample of a radioactive isotope of half-life initially contains N atoms. Which one of the following gives the number of atoms of this isotope that have decayed after a time 3T 1/2 (3 half life)?
Which of the following provides evidence for the existence of neutrons?
The atomic line spectra of elements provides evidence for the existence of
Which of the following provides evidence for the existence of atomic energy levels?
Which of the following statements best describes the random nature of radioactive decay?
Nuclide X has a half-life of 1 day and nuclide Y has a half-life of 5 days. In a particular sample, the activities of X and Y are found to be equal.
When the activity is tested again after 10 days, the activity will be
A nuclide X has a half-life of 10 s. On decay the stable nuclide Y is formed. Initially a sample contains only atoms of X.
After what time will 87.5% of the atoms in the sample have decayed into nuclide Y.
Which of the following best describes why alpha-particles travel only a short distance in air?
Monochromatic light is incident on a metal surface in a photocell. Which of the following statements is correct?