NCERT Science: Matter, Forces, Solutions, and Microorganisms

Vocabulary flashcards covering the particulate nature of matter, types of forces, solutions and density calculations, and cellular and microbial biology from NCERT curriculum modules.

Sublimation

The phase change where a solid transforms directly into a gas upon heating without passing through a liquid state, such as camphor vaporizing and dispersing fragrance throughout a room.

Solid State

A state of matter defined by a fixed shape and a fixed volume, where constituent particles are closely packed in regular arrangements, possess strong interparticle interactions, and vibrate in fixed positions.

Liquid State

A state of matter characterized by a definite volume but no fixed shape, whose particles are close together but free to slide past one another to take the shape of their container.

Gaseous State

A state of matter in which particles are spaced far apart, experience weak intermolecular forces, and move rapidly and randomly in all directions, enabling rapid diffusion and mixing.

Interparticle Attraction in Melting

The weakening of attractive forces holding constituent particles together when thermal energy is added to a solid, allowing particles to transition into a liquid state.

Muscular Force

A contact force exerted through the action of biological muscles, such as a child lifting a school bag.

Magnetic Force

A non-contact force exerted by magnetic fields on magnetic materials or poles, exemplified by a magnetic compass needle aligning itself to point North.

Frictional Force

A contact force that opposes the relative motion between two surfaces in contact, such as the force causing a rolling cricket ball to slow down and stop before the boundary line.

Gravitational Force

A non-contact attractive force exerted by massive bodies that pulls objects downward, such as causing detached fruit to fall from a tree toward Earth.

Electrostatic Force

A force of attraction or repulsion between electrically charged objects, such as two negatively charged rubber balloons repelling each other after being rubbed with wool.

Non-Uniform Motion

Accelerated motion in which an object experiences a change in speed, direction, or both, which always requires the application of a net force.

Weight vs. Mass

Mass is an invariant measure of the amount of matter in an object, whereas weight depends on local gravitational pull; on the Moon, an object's weight is approximately $\frac{1}{6}$ of its weight on Earth, while its mass remains unchanged.

Saturated Solution

A solution that has dissolved the maximum possible amount of solute at a specified temperature, such that no additional solute can dissolve.

Unsaturated Solution

A solution containing less solute than its maximum capacity at a given temperature, capable of dissolving more solute when added.

Solubility

The maximum quantity of solute that can dissolve in a specified solvent at a particular temperature.

Density

A physical property defined as mass per unit volume ($\text{Density} = \frac{\text{Mass}}{\text{Volume}}$), which depends solely on mass and volume rather than external shape and generally decreases as temperature increases.

Displacement Method

A laboratory procedure used to determine the volume of a solid object by submerging it in water and measuring the resulting rise in water level.

Buoyancy Effect of Orange Peel

The principle where an unpeeled orange floats due to air pockets trapped inside its peel lowering its average density below that of water, whereas removing the peel eliminates the air pockets, causing the orange to sink.

Nucleus

A membrane-bound cell organelle found in eukaryotic plant and animal cells (absent in bacteria) that regulates and directs cellular activities.

Cytoplasm

A jelly-like fluid that fills the interior of the cell and suspends all cellular organelles.

Chloroplast

A specialized organelle found exclusively in plant cells that contains chlorophyll and carries out photosynthesis.

Cell Wall

A rigid outer protective layer located outside the cell membrane in plant and bacterial cells, providing structural strength.

Cell Membrane

A semi-permeable biological boundary found in all cells, positioned interior to the cell wall in plants and bacteria, and forming the outermost layer in animal cells.

Nucleoid

An irregularly shaped region in bacterial cells where genetic material ($\text{DNA}$) resides without being enclosed by a nuclear membrane.

Rhizobium

A genus of nitrogen-fixing bacteria living symbiotically within root nodules of leguminous pulse and bean crops, converting atmospheric nitrogen into bioavailable soil nutrients.

Yeast Fermentation

An anaerobic metabolic process in which yeast breaks down sugar into alcohol and carbon dioxide gas ($CO_2$), which is used in baking to make dough fluffy and porous.

Lime Water Test for Carbon Dioxide

A diagnostic chemical reaction in which carbon dioxide ($CO_2$) passes into clear lime water, turning it milky white via the formation of insoluble calcium carbonate ($CaCO_3$).

Composting Carbon-Nitrogen Balance

The optimal ratio of carbon-rich dry plant waste (brown material) to nitrogen-rich fruit/vegetable peel waste (green material) required by decomposer microorganisms to break down matter efficiently without rotting odors.

Lactobacillus

A genus of lactic acid-producing bacteria found in curd that converts lactose into lactic acid; its activity accelerates in warmer temperatures, causing curd to become increasingly sour.