RBSE Secondary Science flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Acid + metal reaction

An acid reacts with a metal to produce a salt and hydrogen gas. Example: Zn + 2HCl → ZnCl2 + H2. The metal must be above hydrogen in the reactivity series.

Neutralisation reaction

A reaction between an acid and a base that produces a salt and water. Example: HCl + NaOH → NaCl + H2O. The pH moves toward 7.

Reactivity series

A list of metals arranged in decreasing order of chemical reactivity: K, Na, Ca, Mg, Al, Zn, Fe, Pb, (H), Cu, Hg, Ag, Au. Metals above hydrogen displace it from acids.

Homologous series

A family of organic compounds with the same general formula and functional group, where successive members differ by one –CH2– unit (14 u). Example: alkanes CnH2n+2.

Periodic table groups

Vertical columns in the periodic table. Elements in the same group have the same number of valence electrons and similar chemical properties. Group 1 is alkali metals.

Mole concept

One mole of a substance contains 6.022×10^23 particles (Avogadro number) and has a mass equal to its molar mass in grams. Number of moles = mass / molar mass.

Photosynthesis equation

6CO2 + 6H2O → C6H12O6 + 6O2 in the presence of chlorophyll and sunlight. It converts light energy into chemical energy stored in glucose.

Aerobic respiration

Breakdown of glucose using oxygen to release energy: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy. Occurs mainly in mitochondria and yields about 38 ATP.

Nephron

The functional unit of the kidney. It filters blood in the glomerulus, reabsorbs useful substances in the tubule, and collects urine in the collecting duct.

Reflex arc

The nerve pathway of a reflex action: receptor → sensory neuron → spinal cord (relay neuron) → motor neuron → effector. It allows a quick response without conscious brain control.

Mendel's law of segregation

During gamete formation, the two alleles of a gene separate so that each gamete receives only one allele. This explains the 3:1 ratio in the F2 generation of a monohybrid cross.

Homologous organs

Organs with the same basic structure and origin but different functions. Example: forelimbs of humans, whales, and bats. They indicate common ancestry (divergent evolution).

Law of reflection

The angle of incidence equals the angle of reflection, and the incident ray, reflected ray, and normal all lie in the same plane. Measured from the normal.

Mirror formula

1/f = 1/v + 1/u, where f is focal length, v is image distance, and u is object distance. Magnification m = -v/u = height of image / height of object.

Snell's law

For light passing from medium 1 to medium 2: n1 sin i = n2 sin r, where i is angle of incidence and r is angle of refraction. It describes bending of light.

Lens formula

1/f = 1/v – 1/u for a lens, with sign convention: distances measured from optical centre. Power of lens P = 1/f (metres), unit dioptre (D).

Myopia

Short-sightedness where distant objects appear blurry because the image forms in front of the retina. Corrected by a concave (diverging) lens of suitable power.

Ohm's law

At constant temperature, the current through a conductor is directly proportional to the potential difference across it: V = IR, where R is resistance in ohms.

Resistance in series

When resistors are connected in series, the total resistance is the sum of individual resistances: R = R1 + R2 + … . Current is the same through each resistor.

Electric power

The rate at which electrical energy is consumed: P = VI = I^2R = V^2/R. Unit is watt (W); commercial unit of energy is kilowatt-hour (kWh).

Magnetic effect of current

A current-carrying conductor produces a magnetic field around it. Field lines are concentric circles for a straight wire, direction given by right-hand thumb rule.

Fleming's left-hand rule

For a current-carrying conductor in a magnetic field, stretch thumb, forefinger, and middle finger mutually perpendicular: forefinger = field, middle = current, thumb = force direction.

Renewable energy sources

Energy sources that are naturally replenished, such as solar, wind, hydro, biomass, and geothermal. They are sustainable and produce little or no greenhouse gases.

10% law of energy transfer

In a food chain, only about 10% of the energy at one trophic level is transferred to the next; the rest is lost as heat and used in life processes.

Ozone depletion

Thinning of the ozone layer in the stratosphere mainly due to chlorofluorocarbons (CFCs). It allows more ultraviolet radiation to reach Earth, harming living organisms.

Sustainable management

Using natural resources in a way that meets present needs without compromising future generations. Includes the 3Rs (reduce, reuse, recycle), rainwater harvesting, and afforestation.

Controlled experiment

An experiment in which the independent variable is changed, the dependent variable is measured, and all other variables are kept constant to ensure a fair test.

Limewater test

Carbon dioxide gas turns limewater (calcium hydroxide solution) milky due to formation of calcium carbonate precipitate: Ca(OH)2 + CO2 → CaCO3 + H2O.

Flame test colours

Metal ions give characteristic flame colours: sodium – golden yellow; potassium – lilac; calcium – brick red; copper – blue-green. Used to identify metal salts.

Precision vs accuracy

Precision is how close repeated measurements are to each other; accuracy is how close a measurement is to the true value. A measurement can be precise but inaccurate.

Meniscus reading

When reading a measuring cylinder, keep the eye level with the bottom of the meniscus (curved surface). Record the value with one estimated digit beyond the smallest division.

Line of best fit

A straight line drawn on a graph that best represents the trend of plotted data points, with roughly equal numbers of points above and below the line.