Explanation

• The Mole (mol) is the SI unit of amount of substance, representing 6.022 x 10^23 particles.
• It is used to measure the amount of a substance in a sample.

Explanation

The average translational kinetic energy of a molecule in an ideal gas is given by the formula:

E=3/2​kT

Where:

• $k = 1.38 times 10^{-23} , text{J/K}$ (Boltzmann constant)

• T=27∘C=300K (since 27°C + 273 = 300 K)

Now calculate:

E=3​/2×1.38×10^−23×300
E=3/2​×4.14×10^−21

6.21×10^−21 J

Explanation

Silicon is a metalloid with properties ideal for controlling electrical current.

It's the most widely used material in semiconductor devices like transistors and chips.

Explanation

In space, beyond Earth's atmosphere, the sky actually looks black because there is no air to scatter sunlight.

The blue color we see from Earth is due to Rayleigh scattering in the atmosphere, not the actual color of the sky.

Explanation

Momentum (p) is proportional to velocity (v), while kinetic energy (KE) is proportional to v².

When momentum decreases by 20%, velocity decreases by 20%.

So, kinetic energy decreases by (1 - 0.8²) × 100% ≈ 36%.

Explanation

Explanation

In a vacuum or free space, there are no particles or matter, so:

• Pressure (p) is zero.
• Current density (J) is also zero, since there are no charged particles to carry current.

Therefore, the correct observation is p = 0, J = 0.

Explanation

Gamma rays are the most dangerous because they have the highest energy.

It can penetrate deep into tissues, causing severe damage to cells and DNA.

Explanation

Echoes are produced when sound waves bounce back after hitting a surface, which is due to the reflection of sound.

This reflected sound is heard as an echo.

Explanation

Homogeneous liquid equilibria can be affected by temperature changes,

It as the temperature can influence the equilibrium position.

Pressure changes may also affect equilibria but to a lesser extent than temperature changes.