CBSE Class 10 Science Syllabus

On what basis did Mendeleev arrange elements, and what was his Periodic Law?

Mendeleev arranged elements by increasing atomic mass. His law: properties of elements are a periodic function of their atomic masses.

State the Modern Periodic Law and the basis of arrangement in the modern periodic table.

Properties of elements are a periodic function of their atomic numbers. Elements are arranged by increasing atomic number (proposed by Moseley).

How many periods and groups are there in the modern periodic table?

7 periods (horizontal rows) and 18 groups (vertical columns).

How do atomic size and metallic character vary across a period and down a group?

Across a period (left to right): atomic size decreases, metallic character decreases. Down a group: atomic size increases, metallic character increases.

Name the four life processes essential for maintaining life in organisms.

Nutrition, respiration, transportation, and excretion (along with control/coordination and reproduction for the species).

Write the balanced equation for photosynthesis and state where it occurs.

6CO2 + 6H2O --(light, chlorophyll)--> C6H12O6 + 6O2. It occurs in the chloroplasts of green plant cells.

Compare aerobic and anaerobic respiration in terms of oxygen, end products, and energy.

Aerobic: uses O2, gives CO2 + water, more energy. Anaerobic: without O2, gives ethanol+CO2 (yeast) or lactic acid (muscles), less energy.

What is the role of the stomata in plants?

Tiny pores on leaves that allow exchange of gases (CO2 and O2) and loss of water vapour (transpiration). They open/close via guard cells.

What are xylem and phloem, and what does each transport in plants?

Xylem transports water and dissolved minerals from roots upward; phloem transports food (sugars) made in leaves to all parts (translocation).

What is the functional unit of the kidney, and what is the process of filtering blood called?

The nephron is the functional unit of the kidney. Blood is filtered by a process called filtration in the glomerulus, then selective reabsorption occurs.

Name the parts of a neuron and the junction between two neurons.

A neuron has dendrites, cell body (cyton), and axon. The junction/gap between two neurons is called a synapse.

Name any three plant hormones and one function of each.

Auxin (cell growth/phototropism), Gibberellin (stem growth), Cytokinin (cell division), Abscisic acid (inhibits growth, closes stomata - 'stress hormone').

What is a reflex action and which part of the nervous system controls it?

A rapid, automatic, involuntary response to a stimulus. It is controlled by the spinal cord through a reflex arc (without involving conscious brain thought).

Name the hormone secreted by the pancreas to regulate blood sugar and the disease caused by its deficiency.

Insulin regulates blood sugar. Its deficiency causes diabetes (high blood sugar levels).

What is the difference between asexual and sexual reproduction?

Asexual: one parent, no gametes, offspring genetically identical (clones). Sexual: two parents, fusion of gametes, offspring show genetic variation.

Name the male and female reproductive parts of a flower.

Male part: stamen (anther + filament). Female part: pistil/carpel (stigma, style, ovary).

What is fertilisation, and where does it occur in the human female?

Fertilisation is the fusion of male gamete (sperm) and female gamete (egg/ovum) to form a zygote. In humans it occurs in the fallopian tube (oviduct).

State Mendel's experimental result for monohybrid cross and the phenotypic ratio in F2.

Crossing tall (TT) x short (tt) gave all tall in F1; F2 showed tall and short in a phenotypic ratio of 3:1 (genotypic ratio 1:2:1).

How is the sex of a child determined in humans?

Mother always contributes X chromosome. If father's sperm carries X -> girl (XX); if it carries Y -> boy (XY). So the father determines the sex.

Differentiate between acquired and inherited traits with an example.

Acquired traits develop during a lifetime and are not passed on (e.g. low body weight from starvation). Inherited traits are passed via genes to offspring (e.g. eye colour).

State the laws of reflection of light.

1) The angle of incidence equals the angle of reflection. 2) The incident ray, reflected ray, and normal at the point of incidence all lie in the same plane.

State the nature, position, and size of the image formed by a plane mirror.

Virtual, erect, same size as the object, laterally inverted, and formed as far behind the mirror as the object is in front.

Write the mirror formula and the magnification formula for a spherical mirror.

Mirror formula: 1/v + 1/u = 1/f. Magnification: m = -v/u = height of image / height of object.

Define refractive index and give Snell's law.

Refractive index n = speed of light in vacuum / speed in medium. Snell's law: sin i / sin r = constant (refractive index of second medium w.r.t. first).

Write the lens formula and state the power of a lens with its SI unit.

Lens formula: 1/v - 1/u = 1/f. Power P = 1/f (in metres), SI unit is dioptre (D).

What happens to a ray of white light when it passes through a glass prism?

It bends towards the base and splits into its seven constituent colours (VIBGYOR) - this dispersion happens because different colours bend by different amounts.

Why is the sky blue and why does the Sun appear red at sunrise/sunset?

Blue sky: shorter blue wavelengths are scattered more by air molecules (Rayleigh scattering). Red Sun: at sunrise/sunset light travels longer through atmosphere, so most blue is scattered away leaving red.

Name the defect of vision in which a person cannot see distant objects clearly and how it is corrected.

Myopia (short-sightedness); image forms in front of the retina. Corrected using a concave (diverging) lens of suitable power.

What is the power of accommodation of the eye and which part is responsible?

The ability of the eye lens to adjust its focal length to focus objects at different distances. The ciliary muscles change the curvature/thickness of the eye lens.

State Ohm's law and write its formula.

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

How does resistance depend on length and area of cross-section of a wire? Give the formula.

R = rho x L / A. Resistance is directly proportional to length (L) and inversely proportional to area of cross-section (A); rho is resistivity.

Write the formula for electric power in three forms.

P = VI = I^2 R = V^2 / R. SI unit is watt (W); 1 unit of electricity = 1 kilowatt-hour (kWh).

State the rule used to find the direction of magnetic field around a straight current-carrying conductor.

Right-hand thumb rule: if the thumb of the right hand points in the direction of current, the curled fingers show the direction of the magnetic field lines.

State Fleming's left-hand rule and what it is used for.

Stretch thumb, forefinger, and middle finger of the left hand perpendicularly: forefinger = field, middle finger = current, thumb = force/motion. Used to find force on a current-carrying conductor in a magnetic field (electric motor).

What is electromagnetic induction and which rule gives the direction of induced current?

Production of induced current in a coil by changing the magnetic field around it. Fleming's right-hand rule gives the direction of induced current (used in generators).

What are the colours of live, neutral, and earth wires in domestic wiring, and the purpose of the earth wire?

Live = red/brown, Neutral = black/blue, Earth = green (or yellow-green). The earth wire is a safety measure that carries leakage current to the ground.

What is a good source of energy? Name any two renewable and two non-renewable sources.

A good source supplies a large amount of energy economically, safely, and is easy to store/transport. Renewable: solar, wind. Non-renewable: coal, petroleum.

What is biogas, what is its main component, and what is the slurry used for?

Biogas is produced by anaerobic decomposition of biomass; its main component is methane (CH4). The leftover slurry is used as an excellent manure/fertiliser.

What is a food chain and what are the trophic levels?

A series of organisms feeding on one another transferring energy. Trophic levels: producers (plants), primary consumers (herbivores), secondary and tertiary consumers (carnivores), and decomposers.

State the 10 percent law of energy flow in an ecosystem.

Only about 10% of the energy at one trophic level is transferred to the next level; the rest is lost as heat. This limits food chains to 3-4 levels.

Differentiate between biodegradable and non-biodegradable substances with one example each.

Biodegradable: broken down by microbes (e.g. paper, food waste). Non-biodegradable: not decomposed by microbes (e.g. plastic, DDT, glass).

How is the ozone layer beneficial and what chemical is mainly responsible for its depletion?

The ozone layer absorbs harmful ultraviolet (UV) radiation from the Sun. Chlorofluorocarbons (CFCs) are mainly responsible for its depletion.

What do the three R's stand for in management of natural resources?

Reduce, Reuse, and Recycle - reducing consumption, reusing items, and recycling materials to conserve natural resources.

What are the advantages and one disadvantage of building large dams?

Advantages: irrigation, electricity generation, water supply. Disadvantages: displacement of people, submergence of forests/land, and loss of biodiversity.

What is rainwater harvesting and name a traditional water harvesting method.

Collecting and storing rainwater for later use and for recharging groundwater. Traditional methods include khadins, tanks, bawris/baolis, and check dams.

Why is the conservation of forests and wildlife important, and who are the stakeholders?

To maintain biodiversity and ecological balance. Stakeholders: local people dependent on forests, the Forest Department, industrialists, and wildlife/nature enthusiasts.