Explanation

The biosphere is the region of the Earth where life exists, including the land, oceans, and atmosphere.

It encompasses all living organisms, from the tiniest microbe to the mightiest tree.

Includes the interactions between living things and their environment.

Explanation

Efficiency is the ratio of output to input, often expressed as a percentage.

It represents how much of the input energy is actually converted into useful output energy, with the rest being lost as waste or heat.

Key Points:

• Energy is the ability to do work.
• Work is the transfer of energy through a force applied over a distance.
• Power is the rate at which work is done or energy is transferred.

Explanation

When a gas is heated in a container of fixed volume, the molecules of the gas:

• Move faster (their kinetic energy increases, causing them to move more rapidly)
• Collide more frequently with the container walls (resulting in increased pressure)
• Do not expand (the container volume is fixed)
• Do not move further apart (the density of the gas remains the same, as the volume

Explanation

Neutral equilibrium is a state where the body is balanced, but the slightest disturbance will not cause it to return to its original position or topple over.

In this state, the center of gravity (CG) remains at the same height, regardless of the slight tilt or displacement.

Key Points: 

• A body is in unstable equilibrium after slight tilt if its center of gravity remains above the point of contact.
  
• A body is in stable equilibrium after slight tilt if its center of gravity remains above the point of contact.
  

Explanation

To find the density of the steel balls, we need to use the formula for density:

Density = Mass/Volume

1. Calculate the total mass of the steel balls:

Each ball has a mass of 27 g, and there are 10 balls.

Total mass = 10 x 27 = 270 g

2. Calculate the volume displaced by the steel balls:

The initial volume of water is 20 cm^3

The final volume of water is 50 cm^3

The volume displaced by the steel balls is:

Volume displaced = 50 cm^3 - 20 cm^3 = 30 cm^3

3. Calculate the density of the steel:

Using the total mass and the volume displaced:

Density = 270 g / 30cm,^3 = 9.0 g/cm^3

Therefore, the density of the steel is 9.0 g/cm^3.

Explanation

Group VIII-A, also known as the noble gases, consists of:

• Helium (He)
• Neon (Ne)
• Argon (Ar)
• Krypton (Kr)
• Xenon (Xe)
• Radon (Rn)

Explanation

• When two identical atoms share electron pairs and exert an equal force on each other, the bond formed is a non-polar covalent bond.
• This type of bond is characterized by a equal sharing of electrons, resulting in a balanced and symmetrical distribution of electrons.

Explanation

• The octet rule states that atoms tend to gain, lose, or share electrons to achieve a full outer energy level, which typically corresponds to eight electrons in the valence shell.
• This rule is a fundamental principle in chemistry and is used to explain the formation of chemical bonds and the structure of molecules.

Explanation

• Ethyl alcohol was prepared by Al-Razi (also known as Rhazes).
• He was a Persian polymath who made significant contributions to chemistry and medicine, including the distillation of alcohol.

Explanation

• The lock and key model proposes that the enzyme and substrate have specific, complementary geometric shapes that fit together perfectly, like a key fitting into a lock.
• This means that the active site of the enzyme is a rigid, pre-formed structure that perfectly complements the shape of the substrate.