In an atom number of protons and neutrons are added to obtain:
(b)
If proton number is 19, electron configuration will be:
If the proton number is 19, the electron configuration would be 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ OR 1S² =2 2s² 2p6=8 3s² 3p6=8 4s¹ =1
If nucleon number of potassium is 39 and its atomic number is 19 then, number of neutrons will be:
To find the number of neutrons in an atom, you subtract the atomic number from the nucleon number. For potassium:
- Nucleon number = 39
- Atomic number = 19
- Number of neutrons = Nucleon number - Atomic number
Number of neutrons = 39 - 19
Number of neutrons = 20
ORn = A-Z
n = 39 - 19
n = 20
So, potassium has 20 neutrons
The isotope C-12 is present in abundance of:
(c)
Electronic configuration is distribution of:
(c)
Which one of the following is most penetrating?
(d)
How many subshells in a L shell:
(b)
De Broglie extend the wave particle duality to electron in:
(b)
Name the material of screen which is used in Rutherford atomic model:
(b)
Which rays are used for sterilization of medical instruments:
(c)
Who discovered the electron?
J.J. Thomson discovered the electron through his cathode ray experiments in 1897.
The proton was discovered by:
Eugen Goldstein discovered protons through his work with canal rays in 1886.
The neutron was discovered by:
James Chadwick discovered the neutron in 1932 by bombarding beryllium with alpha particles.
Cathode rays are composed of:
Cathode rays are streams of electrons observed in vacuum tubes.
Which subatomic particle has no charge?
Neutrons are neutral particles with no electrical charge.
The mass of a proton is approximately how many times that of an electron?
A proton's mass is about 1836 times greater than an electron's mass.
In Rutherford's gold foil experiment, most alpha particles:
Most alpha particles passed through undeflected, showing atoms are mostly empty space.
Rutherford's atomic model proposed that the atom has:
The deflection of alpha particles in Rutherford's experiment indicated that the nucleus is:
The deflection showed the nucleus must be positively charged to repel the positive alpha particles.
Bohr's atomic model was based on the spectrum of which element?
Bohr developed his model to explain the line spectrum of hydrogen, which showed discrete energy levels.
According to Bohr's model, electrons move in:
Bohr proposed that electrons move in specific circular orbits around the nucleus.
The energy of an electron in Bohr's model is:
Bohr's model introduced the concept of quantized energy levels for electrons.
The quantum number 'n' in Bohr's model represents:
The principal quantum number 'n' indicates the energy level or shell of the electron.
De Broglie proposed that electrons have:
De Broglie's wave-particle duality suggested all matter has both particle and wave characteristics.
Schrödinger's atomic model is based on:
Schrödinger's model uses quantum mechanical principles to describe electron behavior.
The shape of an 's' orbital is:
The s orbital has a spherical shape, symmetric around the nucleus.
The maximum number of electrons in the K shell (n=1) is:
The K shell can hold a maximum of 2 electrons (2n² where n=1).
The maximum number of electrons in the L shell (n=2) is:
The L shell can hold up to 8 electrons (2n² where n=2).
The subshells in the L shell are:
The L shell (n=2) contains only s and p subshells.
The electronic configuration of Oxygen (atomic number 8) is:
Oxygen has 8 electrons distributed as 2 in 1s, 2 in 2s, and 4 in 2p orbitals.
Isotopes of an element have the same number of:
Isotopes have identical proton numbers but different neutron numbers.
The most abundant isotope of carbon is:
Carbon-12 makes up about 98.89% of naturally occurring carbon.
Which isotope is used to estimate the age of fossils ?
The atomic number of an element is equal to the number of:
The atomic number (Z) uniquely identifies an element and equals its proton count.
The mass number of an atom is the sum of:
Mass number (A) = Number of protons (Z) + Number of neutrons (N).
Which of the following is NOT a property of cathode rays?
Cathode rays are negatively charged electron beams, not positive.
Canal rays are composed of:
Canal rays are positively charged ions (protons) moving toward the cathode.
The neutron was discovered by bombarding beryllium with:
Chadwick bombarded beryllium with alpha particles to produce neutrons.
Which scientist proposed the nucleus model of the atom?
Ernest Rutherford proposed the nucleus model after his gold foil experiment in 1911.
The energy of a photon is given by:
Planck's equation states photon energy (E) equals Planck's constant (h) times frequency (ν).
The De Broglie wavelength is given by:
De Broglie's equation relates wavelength (λ) to Planck's constant (h) divided by momentum (p).
Schrödinger's model describes electrons as:
The quantum mechanical model represents electrons as probability distributions called orbitals.
The maximum number of electrons in a 'p' subshell is:
Each p subshell has 3 orbitals that can hold 2 electrons each (3 × 2 = 6).
The electronic configuration of Neon (atomic number 10) is:
Neon's 10 electrons completely fill the 1s, 2s, and 2p orbitals.
Which of the following is an isotope of hydrogen?
Hydrogen has three isotopes: protium (¹H), deuterium (²H), and tritium (³H).
Isotopes have the same chemical properties because they have the same:
Chemical properties depend on electron arrangement, which is identical in isotopes.
Which isotope is used in cancer treatment?
Cobalt-60 emits gamma rays used in radiotherapy to destroy cancer cells.
The number of neutrons in Cl3517 is:
Neutrons = Mass number (35) - Atomic number (17) = 18 neutrons.
The number of electrons in Fe5626 is:
In neutral atoms, electrons = protons = atomic number (26).
Which of the following is NOT a limitation of Bohr's model?
Bohr's model only successfully explained hydrogen's spectrum, not other elements.
The isotope U23592 is used in:
Uranium-235 undergoes nuclear fission to produce energy in power plants.
The number of subshells in the N shell (n=4) is:
The N shell (n=4) has four subshells: s, p, d, and f.
Which isotope is used in heart pacemakers?
Plutonium-238's steady decay provides long-term power for pacemakers.
The isotope C146 is used in:
The maximum number of electrons in the M shell (n=3) is:
Maximum electrons = 2n² = 2(3)² = 18 electrons in the M shell.