Explanation

 As a chemical reaction progresses, the concentration of reactants decreases, leading to a decrease in the rate of reaction.

This is because there are fewer reactant particles available to collide and react. 

Explanation

 The answer is All of the above.

The oxidation number of an element can be zero, negative, or positive, depending on the element and its bonding environment. 

Explanation

The Van der Waals constant "a" represents the magnitude of intermolecular attractions.

A higher "a" value means stronger intermolecular forces.

- He and H₂ are very light, nonpolar, and have weak intermolecular forces.

- N₂ is also nonpolar but heavier than He and H₂.

- CH₄ (Methane) is nonpolar but larger and more polarizable, so it has stronger London dispersion forces.

→ Therefore, CH₄ has the highest "a" value among the given options. 

Explanation

In an atom, no two electrons can have the same set of four quantum numbers.

This is known as the Pauli Exclusion Principle.

The four quantum numbers are: 

Explanation

 The charge of cathode ray particles can be determined by passing them through oppositely charged plates. 

Cathode rays are composed of negatively charged particles called electrons.

When these rays pass through an electric field with oppositely charged plates

They are deflected towards the positively charged plate, demonstrating their negative charge. 

Explanation

Each molecule of water (H₂O) has 10 electrons (2 from hydrogen and 8 from oxygen).

Therefore, 1 mole of water has 10 moles of electrons.

So, 10 moles of water have 10 x 10 = 100 moles of electrons.

Explanation

The total energy of a hydrogen atom in its ground state is negative. 

The energy of a hydrogen atom in its ground state is typically represented as -13.6 eV.

A negative energy value indicates that the electron is bound to the nucleus and requires energy to be overcome to escape.

The ground state is the lowest energy level an electron can occupy in a hydrogen atom. 

Explanation

Nitrogen gas (N₂) has a triple covalent bond between the two nitrogen atoms.

This triple bond makes N₂ very stable and unreactive under normal conditions.

Explanation

Gas: No definite shape or volume – Expands to fill any container.

Example: Oxygen, CO₂.

Solid: Fixed shape and volume (e.g., iron).

Liquid: Fixed volume, no fixed shape (e.g., water).

Explanation

In the modern periodic table, there are 7 periods (horizontal rows) and 18 groups (vertical columns).