If mass and velocity are unknown when using de Broglie's wavelength formula, what alternative value must we have to successfully determine the wavelength

The particle momentum, p

Explanation:

A particle's de Broglie's wavelength is an indication of the scale in length where the particle's wave-like properties are important. The symbol of de Broglie wavelength is λ or given as follows;

The de Broglie's wavelength formula is given as follows;

Where;

λ = The wavelength of the particle in meters

v = The velocity of the particle in meters/seconds

m = The mass of the particle in kilograms

p = The momentum of the particle

h = Planck's constant = 6.626 × 10⁻³⁴ J/Hz

Therefore, the alternative value that we must have to successfully determine the wavelength if the mass and velocity are unknown, is the momentum, p of the particle.

(75°f − 32) × 5/9 = 23.889°c

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.