Among the elements in group 7A, the most reactive would be Fluorine. Fluorine is a major component of toothpaste, what we use to brush and clean our teeth with. It is so reactive that it cannot be contained in glass.
The answer is C..........
The change in pitch of a train's horn as it passes while you are standing still can be explained by the Doppler effect. The correct option among all the options given in the question is option "A". When the sound source from the horn of the train comes closer, the sound seems to come closer each time a sound wave gets emitted. So it comes closer to us in a bunched form. The reverse happens when the train has just passed with each emitted sound going further and further away. The frequency of the sound seems to get lower as the train moves further away.
The correct answer is:
<span>C: in the protons and neutrons of an atom
In fact, the nuclear energy refers to the binding energy of the nucleons (protons and neutrons) of an atom. The protons and the neutrons are held together by the strong nuclear interaction, one of the four fundamental forces of nature, and the energy associated to this interaction is called nuclear energy.
</span>
Answer:
f>1000Hz and wavelength=0.343 m
Explanation:
We are given that
Frequency of stationary siren,f=1000 Hz
Wavelength of stationary sound,
When a observer is moving towards the siren then the frequency increases.
Therefore,an observer who is moving towards the siren measure a frequency >1000 Hz.
The wavelength depends upon the speed of source.
But we are given that siren is stationary.
Therefore, source is not moving and then the wavelength remains same.
f>1000Hz and wavelength=0.343 m
