## Question

An ion with mass number 56 contains 3 units of positive charge and 30.4% more neutrons than electrons. Assign the symbol to this ion.

### Solution

Suppose number of electrons in the ion, M^{3+} = *x*

No. of electrons in the neutral atom = *x* + 3

∴ No. of protons = *x* + 3

Mass no. = No. of protons + No. of neutrons

∴ No. of protons = Atomic no. = *x* + 3 = 23 + 3 = 26.

Hence, the symbol of the ion will be .

#### SIMILAR QUESTIONS

What is the transition in the hydrogen spectrum would have the same wavelength as the Balmer transition, *n* = 4 to *n* = 2 of He^{+} spectrum?

Calculate the energy required for the process

He^{+} (*g*) → He^{2+} (*g*) + *e*^{–}

The ionization energy for the H atom in the ground state is

2.18 × 10^{–18} J atom^{–1}.

A 25 watt bulb emits monochromatic yellow light of wavelength of 0.57 μm. Calculate the rate of emission of quanta per second.

What is the wavelength of the light emitted when the electron in a hydrogen atom undergoes transition from an energy level with *n* = 4 to an energy level with *n* = 2? What is the colour corresponding to this wavelength? (Rydberg constant = 109,677 cm^{–1})

A certain particle carries 2.5 × 10^{–16} C of static electric charge. Calculate the number of electrons present in it.

An ion with mass number 37 possesses one unit of negative charge. If the ion contains 11.1% more neutrons then the electrons, find the symbol of the ion.

Nitrogen laser produces a radiation at a wavelength of 337.1 nm. If the number of photons emitted is 5.6 × 10^{24}, calculate the power of this laser.

The angular momentum of an electron in Bohr’s orbital of hydrogen atom is 4.22× 10^{–34} kg m^{2}s^{–1}. Calculate the wavelength of the spectral line when the electron falls from this level to the next lower level.

With what velocity must an electron travel so that its momentum is equal to that of a photon of wavelength 560 nm?

If uncertainties in the measurement of position and momentum of an electron are found to be equal in magnitude, what is the uncertainty in the measurement of velocity of the electron? Comment on the result obtained.