NCERT concepts questions and answers
Concept-based practice inspired by school learning, with class and subject labels.
The NCERT label describes the intended study track, not an endorsement or a verified mapping to the latest syllabus. These are practice variations, many generated from templates and numeric inputs, not an official question bank. They remain outside search indexing until at least 100 independently reviewed questions across five chapters are available.
Questions and clear answers
01Science · foundation · Editorial previewWhat is the difference between a physical and a chemical change?+
A physical change changes form or state without making a new substance; a chemical change forms new substances.
02Physics · foundation · Editorial previewWhy do opaque objects create shadows?+
They block rays of light from reaching the region behind them, producing a darker area.
03Mathematics · foundation · Editorial previewWhy does multiplying length by breadth give rectangle area?+
It counts the unit squares arranged along the two perpendicular dimensions of a rectangle.
04Biology · foundation · Editorial previewWhat does chlorophyll do in photosynthesis?+
Chlorophyll absorbs light energy that supports photosynthetic reactions in plants and algae.
05Mathematics · Arithmetic and number systems · advanced · Editorial previewIn ncert — Arithmetic and number systems: A practice worksheet lists 79 objects and then 2 more. How many objects are there in total?+
Add the two quantities: 79 + 2 = 81 objects in total.
06Mathematics · Algebra · foundation · Editorial previewIn ncert — Algebra: Solve 24x + 34 = 16594 for x.+
Subtract 34 and divide by 24: x = 690.
07Mathematics · Geometry · foundation · Editorial previewIn ncert — Geometry: A rectangular study space is 1301 m long and 7 m wide. Find its area.+
Area = length × width = 1301 × 7 = 9107 m².
08Mathematics · Statistics · intermediate · Editorial previewIn ncert — Statistics: Four measurements are 1912, 39, 1933 and 60. What is their arithmetic mean?+
Sum = 3944; divide by 4 to get 986.
09Physics · Motion · foundation · Editorial previewIn ncert — Motion: A vehicle travels at a constant 2523 km/h for 22 hours. How far does it travel?+
Distance = speed × time = 2523 × 22 = 55506 km.
10Physics · Force · advanced · Editorial previewIn ncert — Force: An object of mass 6 kg accelerates at 6 m/s². Find the net force.+
Newton's second law: F = ma = 6 × 6 = 36 newtons.
11Physics · Electricity · intermediate · Editorial previewIn ncert — Electricity: A resistor of 13 Ω carries 13 A of current. Find the voltage.+
V = IR = 13 × 13 = 169 volts, assuming Ohm's law applies.
12Chemistry · Atoms and molecules · foundation · Editorial previewIn ncert — Atoms and molecules: Each of 3 identical containers holds 360 g of water. Using molar mass 18 g/mol, how many moles are there across all containers?+
Total mass = 3 × 360 g; moles = total mass/18 = 60 mol.
13Chemistry · Solutions · foundation · Editorial previewIn ncert — Solutions: Dissolve 4 mol of solute and make up 10 litres of solution. Find molarity.+
Molarity = moles/volume = 4/10 ≈ 0.4 mol/L.
14Chemistry · Reactions · intermediate · Editorial previewIn ncert — Reactions: In a closed reaction, 579 g of one reactant combines completely with 54 g of another. Find the total product mass.+
Conservation of mass: 579 + 54 = 633 g (assuming all matter is accounted for).
15Mathematics · Ratios · advanced · Editorial previewIn ncert — Ratios: Split 21906 items between two groups in the ratio 1190:27. How many go to the first group?+
The total ratio is 1217 parts. First group = 21906 × 1190/1217 = 21420.
16General Science · Percentage · foundation · Editorial previewIn ncert — Percentage: A sample has 1860 units, of which 1801 meet the stated condition. What percentage meet it, rounded to two decimals?+
96.83% because 1801 ÷ 1860 × 100 = 96.83%.
17Mathematics · Arithmetic and number systems · intermediate · Editorial previewIn ncert — Arithmetic and number systems: A practice worksheet lists 2412 objects and then 32 more. How many objects are there in total?+
Add the two quantities: 2412 + 32 = 2444 objects in total.
18Mathematics · Algebra · foundation · Editorial previewIn ncert — Algebra: Solve 16x + 5 = 48373 for x.+
Subtract 5 and divide by 16: x = 3023.
This is an educational practice preview. Answers and board-specific alignment are undergoing editorial review; these are not official exam questions.