Explanation

• De Broglie extended the wave-particle duality to electrons in 1923.
• He proposed that particles such as electrons exhibit wave-like properties.
• A hypothesis that was later confirmed experimentally and became a fundamental concept in quantum mechanics.

Explanation

The L shell, also known as the second electron shell, has 02 subshells:

The L shell contains two subshells - 2s, 2p.

The M shell contains three subshells - 3s, 3p, 3d.

The N shell contains four subshells - 4s, 4p, 4d, 4f

Explanation

• Neutrons are the most penetrating, because they have no charge and a relatively large mass compared to electrons and protons.
• This allows them to travel long distances through matter without being deflected or absorbed, making them highly penetrating.

Explanation

• Carbon-12 (C-12) is the most abundant of the two stable isotopes of carbon, amounting to 98.93% of elemental carbon on Earth.
• Carbon-12 is composed of six protons, six neutrons, and six electrons.
• The atomic mass of carbon-12 is exactly 12 Dalton's, by definition.

Explanation

• The nucleon number (mass number) of Potassium is 39, and the atomic number (number of protons) is 19.
• To find the number of neutrons, subtract the number of protons from the nucleon number:
• 39 (nucleon number) - 19 (proton number) = 20
• So, the number of neutrons in Potassium-39 is 20.

Explanation

• The atomic number 19 corresponds to the element Potassium (K).
• The electron configuration of Potassium is: 1s² 2s² 2p⁶ 3s¹
• Which can be simplified to: 2, 8, 8, 1.

Explanation

• The number of protons and neutrons in an atom are added together to obtain the total number of nucleons.
• It is also known as the mass number.

Explanation

• A substance is a piece of matter in pure form, with a specific composition and properties.
• It can be either an element or a compound.

Explanation

• The empirical formula of hydrogen peroxide (H2O2) is HO.
• The empirical formula is the simplest whole-number ratio of atoms of each element in a compound.
• In this case, the ratio of hydrogen to oxygen is 1:1, which is represented by the formula HO.

Explanation

• H2 is only a homo atomic [homo: same] molecule.
• Rest three are hetero atomic [hetero: different] molecules).