Explanation

Barium (Z = 56) → Electron configuration:

[Xe]6s²

Barium's electron distribution:

• K = 2
• L = 8
• M = 18
• N = 18 ⬅ Penultimate shell (4th shell / N-shell)
• O = 8 (valence shell)

The penultimate shell (N-shell) holds 18 electrons in Barium.

Explanation

Step 1: Calculate the molar mass of S8

The atomic mass of sulfur (S) is approximately 32 g/mol. The molar mass of S8 = 8 * 32 = 256 g/mol.

Step 2: Calculate the number of moles of S8

Number of moles = mass of S8 / molar mass of S8 = 64 g / 256 g/mol = 0.25 mol.

Step 3: Calculate the number of molecules of S8

Number of molecules = number of moles * Avogadro's number (NA) = 0.25 * NA.

Step 4: Calculate the number of sulfur atoms

Each molecule of S8 contains 8 sulfur atoms. Therefore, the total number of sulfur atoms = 8 * number of molecules = 8 * 0.25 * NA = 2 * NA = 2NA.

Explanation

To find acceleration, we use the formula:

a = (v - u) / t

where:

v = final velocity = 15 m/s

u = initial velocity = 10 m/s

t = time = 4 seconds

a = (15 - 10) / 4

= 5 / 4

= 1.25 m/s²

Explanation

Maxwell's equations led to the derivation of the speed of electromagnetic waves, including light.

The speed of light (c) is given by C = 1/√μ₀ε₀, where μ₀ is the permeability of free space and ε₀ is the permittivity of free space.

Explanation

The frequency heard by the observer as the car approaches is given by the Doppler effect formula:

f' = f * (v / (v - v_s))

where f = 500 Hz, v = 340 m/s, and v_s = 20 m/s.

f' = 500 * (340 / (340 - 20))

= 500 * (340 / 320)

= 500 * 1.0625

= 531.25 Hz

Explanation

Explanation

The Nearctic region includes North America, where animals like prairie dogs, buzzards, opossums, and mountain lions/dogs are commonly found.

It is one of the major biogeographic realms.

Explanation

The ABO blood group gene is located on chromosome number 9.

It codes for glycosyltransferase enzymes that determine blood type.

Explanation

A terrestrial food chain typically starts with a producer (like grass), followed by primary consumers (herbivores like grasshoppers), then secondary consumers (like snakes), and ends with top predators (like eagles).

This sequence shows the correct flow of energy from plants to top carnivores.

Explanation

In SHM, total energy (kinetic + potential) remains constant if no external force or damping is present.

Though kinetic and potential energy change with time, their sum stays the same throughout the motion.